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+
+# Table of Contents
+
+1.  [Changelog for ELynx](#org9916021)
+
+
+<a id="org9916021"></a>
+
+# Changelog for ELynx
+
diff --git a/LICENSE b/LICENSE
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+++ b/LICENSE
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+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
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+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/README.md b/README.md
new file mode 100644
--- /dev/null
+++ b/README.md
@@ -0,0 +1,417 @@
+
+
+# The ELynx Suite
+
+Version: 0.0.1.
+Reproducible evolution made easy.
+
+The ELynx Suite is a Haskell library and a tool set for computational biology.
+The goal of the ELynx Suite is reproducible research. Evolutionary sequences and
+phylogenetic trees can be read, viewed, modified and simulated. Exact
+specification of all options is necessary, and nothing is assumed about the data
+(e.g., the type of code). The command line with all arguments is consistently,
+and automatically logged. The work overhead in the beginning usually pays off in
+the end.
+
+The Elynx Suite consists of three library packages and two executables providing
+a range of sub commands.
+
+The library packages are:
+
+-   **elynx-seq:** Handle evolutionary sequences and multi sequence alignments;
+-   **elynx-tree:** Handle phylogenetic trees;
+-   **elynx-tools:** Tools for the provided executables;
+
+The executables are:
+
+-   **SLynx:** Analyze, modify, and simulate evolutionary sequences (FASTA format);
+-   **TLynx:** Analyze, modify, and simulate phylogenetic trees (Newick format).
+
+**ELynx is still under development. We happily receive comments, ideas, feature
+requests, or pull requests!**
+
+
+# Installation
+
+ELynx is written in [Haskell](https://www.haskell.org/) and can be installed with [Stack](https://docs.haskellstack.org/en/stable/README/).
+
+1.  Install Stack with your package manager, or directly from the web
+    page.
+    
+        curl -sSL https://get.haskellstack.org/ | sh
+
+2.  Clone the ELynx repository.
+    
+        git clone clone https://github.com/dschrempf/elynx
+
+3.  Navigate to the newly created `elynx` folder and build the binaries.
+    This will take a while.
+    
+        stack build
+
+4.  Run a binary from within the project directory. For example,
+    
+        stack exec tlynx -- --help
+
+5.  If needed, install the binaries.
+    
+        stack install
+    
+    The binaries are installed into `~/.local/bin/` which has to be added [PATH](https://en.wikipedia.org/wiki/PATH_(variable)).
+    Then, they can be used directly.
+
+
+# SLynx
+
+Handle evolutionary sequences.
+
+    slynx --help
+
+    ELynx Suite version 0.5.1. Developed by Dominik Schrempf. Compiled on September
+    9, 2019, at 10:48 am, UTC.
+    
+    Usage: slynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] COMMAND
+      Analyze, and simulate multi sequence alignments.
+    
+    Available options:
+      -h,--help                Show this help text
+      -V,--version             Show version
+      -v,--verbosity VALUE     Be verbose; one of: Quiet Warning Info
+                               Debug (default: Info)
+      -o,--output-file-basename NAME
+                               Specify base name of output file
+    
+    Available commands:
+      concatenate              
+      examine                  If data is a multi sequence alignment, additionally
+                               analyze columns.
+      filter-rows              
+      filter-columns           
+      simulate                 
+      sub-sample               Create a given number of multi sequence alignments,
+                               each of which containing a given number of random
+                               sites drawn from the original multi sequence
+                               alignment.
+      translate                
+    
+    File formats:
+      - FASTA
+    
+    Alphabet types:
+      - DNA (nucleotides)
+      - DNAX (nucleotides; including gaps)
+      - DNAI (nucleotides; including gaps, and IUPAC codes)
+      - Protein (amino acids)
+      - ProteinX (amino acids; including gaps)
+      - ProteinS (amino acids; including gaps, and translation stops)
+      - ProteinI (amino acids; including gaps, translation stops, and IUPAC codes)
+    
+    The ELynx Suite.
+    A Haskell library and a tool set for computational biology. The goal of the
+    ELynx Suite is reproducible research. Evolutionary sequences and phylogenetic
+    trees can be read, viewed, modified and simulated. Exact specification of all
+    options is necessary, and nothing is assumed about the data (e.g., the type of
+    code). The command line with all arguments is consistently, and automatically
+    logged. The work overhead in the beginning usually pays off in the end.
+    slynx     Analyze, modify, and simulate evolutionary sequences.
+    tlynx     Analyze, modify, and simulate phylogenetic trees.
+
+
+## Concatenate
+
+Concatenate multi sequence alignments.
+
+    slynx concatenate --help
+
+    Concatenate sequences found in input files.
+    
+    Usage: slynx concatenate (-a|--alphabet NAME) INPUT-FILE
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      -h,--help                Show this help text
+
+
+## Examine
+
+Examine sequence with `slynx examine`.
+
+    slynx examine --help
+
+    Examine sequences.
+    
+    Usage: slynx examine (-a|--alphabet NAME) [INPUT-FILE] [--per-site]
+      If data is a multi sequence alignment, additionally analyze columns.
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      --per-site               Report per site summary statistics
+      -h,--help                Show this help text
+
+
+## Filter
+
+Filter sequences with `filer-rows`.
+
+    slynx filter-rows --help
+
+    Filter rows (or sequences) found in input files.
+    
+    Usage: slynx filter-rows (-a|--alphabet NAME) [INPUT-FILE]
+                             [--longer-than LENGTH] [--shorter-than LENGTH]
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      --longer-than LENGTH     Only keep sequences longer than LENGTH
+      --shorter-than LENGTH    Only keep sequences shorter than LENGTH
+      -h,--help                Show this help text
+
+Filter columns of multi sequence alignments with `filter-columns`.
+
+    slynx filter-columns --help
+
+    Filter columns of multi-sequence alignments.
+    
+    Usage: slynx filter-columns (-a|--alphabet NAME) [INPUT-FILE]
+                                [--standard-chars DOUBLE]
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      --standard-chars DOUBLE  Keep columns with a proportion standard (non-IUPAC)
+                               characters larger than DOUBLE in [0,1]
+      -h,--help                Show this help text
+
+
+## Simulate
+
+Simulate sequences with `slynx simulate`.
+
+    slynx simulate --help
+
+    Simulate multi sequence alignments.
+    
+    Usage: slynx simulate (-t|--tree-file Name) [-s|--substitution-model MODEL]
+                          [-m|--mixture-model MODEL] [-e|--edm-file NAME]
+                          [-w|--mixture-model-weights "[DOUBLE,DOUBLE,...]"]
+                          [-g|--gamma-rate-heterogeneity "(NCAT,SHAPE)"]
+                          (-l|--length NUMBER) [-S|--seed [INT]]
+    
+    Available options:
+      -t,--tree-file Name      Read trees from file NAME
+      -s,--substitution-model MODEL
+                               Set the phylogenetic substitution model; available
+                               models are shown below (mutually exclusive with -m
+                               option)
+      -m,--mixture-model MODEL Set the phylogenetic mixture model; available models
+                               are shown below (mutually exclusive with -s option)
+      -e,--edm-file NAME       Empirical distribution model file NAME in Phylobayes
+                               format
+      -w,--mixture-model-weights "[DOUBLE,DOUBLE,...]"
+                               Weights of mixture model components
+      -g,--gamma-rate-heterogeneity "(NCAT,SHAPE)"
+                               Number of gamma rate categories and shape parameter
+      -l,--length NUMBER       Set alignment length to NUMBER
+      -S,--seed [INT]          Seed for random number generator; list of 32 bit
+                               integers with up to 256 elements (default: random)
+      -h,--help                Show this help text
+    
+    Substitution models:
+    -s "MODEL[PARAMETER,PARAMETER,...]{STATIONARY_DISTRIBUTION}"
+       Supported DNA models: JC, HKY.
+         For example,
+           -s HKY[KAPPA]{DOUBLE,DOUBLE,DOUBLE,DOUBLE}
+       Supported Protein models: Poisson, Poisson-Custom, LG, LG-Custom, WAG, WAG-Custom.
+         MODEL-Custom means that only the exchangeabilities of MODEL are used,
+         and a custom stationary distribution is provided.
+         For example,
+           -s LG-Custom{...}
+    
+    Mixture models:
+    -m "MIXTURE(SUBSTITUTION_MODEL_1,SUBSTITUTION_MODEL_2)"
+       For example,
+         -m "MIXTURE(JC,HKY[6.0]{0.3,0.2,0.2,0.3})"
+    Mixture weights have to be provided with the -w option.
+    
+    Special mixture models:
+    -m CXX
+       where XX is 10, 20, 30, 40, 50, or 60; CXX models, Quang et al., 2008.
+    -m "EDM(EXCHANGEABILITIES)"
+       Arbitrary empirical distribution mixture (EDM) models.
+       Stationary distributions have to be provided with the -e option.
+       For example,
+         LG exchangeabilities with stationary distributions given in FILE.
+         -m "EDM(LG-Custom)" -e FILE
+    For special mixture models, mixture weights are optional.
+
+
+## Sub-sample
+
+Sub-sample columns from multi sequence alignments.
+
+    slynx sub-sample --help
+
+    Usage: slynx sub-sample (-a|--alphabet NAME) [INPUT-FILE]
+                            (-n|--number-of-sites INT)
+                            (-m|--number-of-alignments INT) [-S|--seed [INT]]
+      Create a given number of multi sequence alignments, each of which containing a
+      given number of random sites drawn from the original multi sequence alignment.
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      -n,--number-of-sites INT Number of sites randomly drawn with replacement
+      -m,--number-of-alignments INT
+                               Number of multi sequence alignments to be created
+      -S,--seed [INT]          Seed for random number generator; list of 32 bit
+                               integers with up to 256 elements (default: random)
+      -h,--help                Show this help text
+
+
+## Translate
+
+Translate sequences.
+
+    slynx translate --help
+
+    Translate from DNA to Protein or DNAX to ProteinX.
+    
+    Usage: slynx translate (-a|--alphabet NAME) [INPUT-FILE]
+                           (-r|--reading-frame INT) (-u|--universal-code CODE)
+    
+    Available options:
+      -a,--alphabet NAME       Specify alphabet type NAME
+      INPUT-FILE               Read sequences from INPUT-FILE
+      -r,--reading-frame INT   Reading frame [0|1|2].
+      -u,--universal-code CODE universal code; one of: Standard,
+                               VertebrateMitochondrial.
+      -h,--help                Show this help text
+
+
+# TLynx
+
+Handle phylogenetic trees in Newick format.
+
+    tlynx --help
+
+    ELynx Suite version 0.5.1. Developed by Dominik Schrempf. Compiled on September
+    9, 2019, at 10:48 am, UTC.
+    
+    Usage: tlynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] COMMAND
+      Compare, examine, and simulate phylogenetic trees.
+    
+    Available options:
+      -h,--help                Show this help text
+      -V,--version             Show version
+      -v,--verbosity VALUE     Be verbose; one of: Quiet Warning Info
+                               Debug (default: Info)
+      -o,--output-file-basename NAME
+                               Specify base name of output file
+    
+    Available commands:
+      compare                  
+      examine                  
+      simulate                 Simulate reconstructed trees using the point process.
+                               See Gernhard, T. (2008). The conditioned
+                               reconstructed process. Journal of Theoretical
+                               Biology, 253(4), 769–778.
+                               http://doi.org/10.1016/j.jtbi.2008.04.005
+    
+    File formats:
+      - Newick
+    
+    The ELynx Suite.
+    A Haskell library and a tool set for computational biology. The goal of the
+    ELynx Suite is reproducible research. Evolutionary sequences and phylogenetic
+    trees can be read, viewed, modified and simulated. Exact specification of all
+    options is necessary, and nothing is assumed about the data (e.g., the type of
+    code). The command line with all arguments is consistently, and automatically
+    logged. The work overhead in the beginning usually pays off in the end.
+    slynx     Analyze, modify, and simulate evolutionary sequences.
+    tlynx     Analyze, modify, and simulate phylogenetic trees.
+
+
+## Compare
+
+Compute distances between phylogenetic trees.
+
+    tlynx compare --help
+
+    Compute distances between phylogenetic trees.
+    
+    Usage: tlynx compare (-d|--distance MEASURE) [-s|--summary-statistics]
+                         [INPUT-FILES]
+    
+    Available options:
+      -d,--distance MEASURE    Type of distance to calculate (available distance
+                               measures are listed below)
+      -s,--summary-statistics  Report summary statistics only
+      INPUT-FILES              Read tree(s) from INPUT-FILES; if more files are
+                               given, one tree is expected per file
+      -h,--help                Show this help text
+    
+    Available distance measures:
+      Symmetric distance: -d symmetric
+      Incompatible split distance: -d incompatible-split[VAL]
+        Collapse branches with support less than VAL before distance calculation;
+        in this way, only well supported difference contribute to the distance measure.
+
+
+## Examine
+
+Compute summary statistics of phylogenetic trees.
+
+    tlynx examine --help
+
+    Compute summary statistics of phylogenetic trees.
+    
+    Usage: tlynx examine [INPUT-FILE]
+    
+    Available options:
+      INPUT-FILE               Read trees from INPUT-FILE
+      -h,--help                Show this help text
+
+
+## Simulate
+
+Simulate phylogenetic trees using birth and death processes.
+
+    tlynx simulate --help
+
+    Simulate phylogenetic trees using birth and death processes.
+    
+    Usage: tlynx simulate [-t|--nTrees INT] [-n|--nLeaves INT] [-H|--height DOUBLE]
+                          [-M|--condition-on-mrca] [-l|--lambda DOUBLE]
+                          [-m|--mu DOUBLE] [-r|--rho DOUBLE] [-u|--sub-sample]
+                          [-s|--summary-statistics] [-S|--seed [INT]]
+      Simulate reconstructed trees using the point process. See Gernhard, T. (2008).
+      The conditioned reconstructed process. Journal of Theoretical Biology, 253(4),
+      769–778. http://doi.org/10.1016/j.jtbi.2008.04.005
+    
+    Available options:
+      -t,--nTrees INT          Number of trees (default: 10)
+      -n,--nLeaves INT         Number of leaves per tree (default: 5)
+      -H,--height DOUBLE       Fix tree height (no default)
+      -M,--condition-on-mrca   Do not condition on height of origin but on height of
+                               MRCA
+      -l,--lambda DOUBLE       Birth rate lambda (default: 1.0)
+      -m,--mu DOUBLE           Death rate mu (default: 0.9)
+      -r,--rho DOUBLE          Sampling probability rho (default: 1.0)
+      -u,--sub-sample          Perform sub-sampling; see below.
+      -s,--summary-statistics  Only output number of children for each branch
+      -S,--seed [INT]          Seed for random number generator; list of 32 bit
+                               integers with up to 256 elements (default: random)
+      -h,--help                Show this help text
+    
+    Height of Trees: if no tree height is given, the heights will be randomly drawn from the expected distribution given the number of leaves, the birth and the death rate.
+    Summary statistics only: only print (NumberOfExtantChildren BranchLength) pairs for each branch of each tree. The trees are separated by a newline character.
+    Sub-sampling: simulate one big tree with n'=round(n/rho), n'>=n, leaves, and randomly sample sub-trees with n leaves. Hence, with rho=1.0, the same tree is reported over and over again.
+
+
+# ELynx
+
+Documentation of the library can be found on Hackage.
+
diff --git a/app/Main.hs b/app/Main.hs
new file mode 100644
--- /dev/null
+++ b/app/Main.hs
@@ -0,0 +1,44 @@
+{- |
+Module      :  Main
+Description :  Work with molecular sequence data
+Copyright   :  (c) Dominik Schrempf 2019
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Thu Sep  5 21:53:07 2019.
+
+-}
+
+module Main where
+
+import           Control.Monad.Trans.Reader
+
+import           Options
+
+import           Concatenate.Concatenate
+import           Examine.Examine
+import           Filter.Filter
+import           Simulate.Simulate
+import           SubSample.SubSample
+import           Translate.Translate
+
+import           ELynx.Tools.Logger
+import           ELynx.Tools.Options
+
+main :: IO ()
+main = do
+  Arguments g c <- parseArguments
+  let fn  = outFileBaseName g
+      lvl = verbosity g
+      lf  = (++ ".log") <$> fn
+  case c of
+    Concatenate a -> runReaderT   (eLynxWrapper lvl lf concatenateHeader   $ concatenateCmd fn) a
+    Examine a -> runReaderT       (eLynxWrapper lvl lf examineHeader       $ examineCmd fn) a
+    FilterRows a -> runReaderT    (eLynxWrapper lvl lf filterRowsHeader    $ filterRowsCmd fn) a
+    FilterColumns a -> runReaderT (eLynxWrapper lvl lf filterColumnsHeader $ filterColumnsCmd fn) a
+    Simulate a -> runReaderT      (eLynxWrapper lvl lf simulateHeader      $ simulateCmd fn) a
+    SubSample a -> runReaderT     (eLynxWrapper lvl lf subSampleHeader     $ subSampleCmd fn) a
+    Translate a -> runReaderT     (eLynxWrapper lvl lf translateHeader     $ translateCmd fn) a
diff --git a/app/Options.hs b/app/Options.hs
new file mode 100644
--- /dev/null
+++ b/app/Options.hs
@@ -0,0 +1,129 @@
+{- |
+Module      :  Options
+Description :  SLynx general options
+Copyright   :  (c) Dominik Schrempf 2019
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sat Sep  7 18:55:03 2019.
+
+-}
+
+module Options
+  ( Arguments (..)
+  , CommandArguments (..)
+  , parseArguments
+  , concatenateHeader
+  , examineHeader
+  , filterRowsHeader
+  , filterColumnsHeader
+  , simulateHeader
+  , subSampleHeader
+  , translateHeader
+  ) where
+
+import           Options.Applicative
+import           Options.Applicative.Help.Pretty
+
+import           Concatenate.Options
+import           Examine.Options
+import           Filter.Options
+import           Simulate.Options
+import           SubSample.Options
+import           Translate.Options
+
+import           ELynx.Data.Alphabet.Alphabet
+import           ELynx.Tools.Options
+
+data CommandArguments =
+  Concatenate ConcatenateArguments
+  | Examine ExamineArguments
+  | FilterRows FilterRowsArguments
+  | FilterColumns FilterColumnsArguments
+  | Simulate SimulateArguments
+  | SubSample SubSampleArguments
+  | Translate TranslateArguments
+
+concatenateHeader, examineHeader, filterRowsHeader, filterColumnsHeader, simulateHeader, subSampleHeader, translateHeader :: String
+concatenateHeader   = "Concatenate sequences found in input files."
+examineHeader       = "Examine sequences."
+filterRowsHeader    =  "Filter rows (or sequences) found in input files."
+filterColumnsHeader = "Filter columns of multi-sequence alignments."
+simulateHeader      = "Simulate multi sequence alignments."
+subSampleHeader     =  "Sub-sample columns from multi sequence alignments."
+translateHeader     =  "Translate from DNA to Protein or DNAX to ProteinX."
+
+concatenateCommand :: Mod CommandFields CommandArguments
+concatenateCommand = command "concatenate" $
+                     info (Concatenate <$> concatenateArguments)
+                     $ header concatenateHeader
+
+examineCommand :: Mod CommandFields CommandArguments
+examineCommand = command "examine" $
+                     info (Examine <$> examineArguments)
+                     ( fullDesc
+                       <> header examineHeader
+                       <> progDesc "If data is a multi sequence alignment, additionally analyze columns." )
+
+filterRowsCommand :: Mod CommandFields CommandArguments
+filterRowsCommand = command "filter-rows" $
+                     info (FilterRows <$> filterRowsArguments)
+                     $ header filterRowsHeader
+
+filterColumnsCommand :: Mod CommandFields CommandArguments
+filterColumnsCommand = command "filter-columns" $
+                     info (FilterColumns <$> filterColumnsArguments)
+                     $ header filterColumnsHeader
+
+simulateCommand :: Mod CommandFields CommandArguments
+simulateCommand = command "simulate" $
+                  info (Simulate <$> simulateArguments)
+                  (fullDesc
+                   <> header simulateHeader
+                   <> footerDoc (Just $ pretty simulateFooter) )
+
+subSampleCommand :: Mod CommandFields CommandArguments
+subSampleCommand = command "sub-sample" $
+                   info (SubSample <$> subSampleArguments)
+                   ( fullDesc
+                     <> header subSampleHeader
+                     <> progDesc "Create a given number of multi sequence alignments, each of which containing a given number of random sites drawn from the original multi sequence alignment." )
+
+translateCommand :: Mod CommandFields CommandArguments
+translateCommand = command "translate" $
+                   info (Translate <$> translateArguments)
+                   $ header translateHeader
+
+commandArguments :: Parser CommandArguments
+commandArguments = hsubparser $
+                   concatenateCommand
+                   <> examineCommand
+                   <> filterRowsCommand
+                   <> filterColumnsCommand
+                   <> simulateCommand
+                   <> subSampleCommand
+                   <> translateCommand
+
+data Arguments = Arguments
+  { globalArgs :: GlobalArguments
+  , cmdArgs    :: CommandArguments }
+
+parseArguments :: IO Arguments
+parseArguments = parseArgumentsWith desc ftr $
+                 Arguments
+                 <$> globalArguments
+                 <*> commandArguments
+
+desc :: [String]
+desc = [ "Analyze, and simulate multi sequence alignments." ]
+
+ftr :: [String]
+ftr = [ "File formats:" ] ++ fs ++
+      [ "", "Alphabet types:" ] ++ as
+  where
+    toListItem = ("  - " ++)
+    fs = map toListItem ["FASTA"]
+    as = map (toListItem . alphabetNameVerbose) [(minBound :: Alphabet) ..]
diff --git a/slynx.cabal b/slynx.cabal
new file mode 100644
--- /dev/null
+++ b/slynx.cabal
@@ -0,0 +1,105 @@
+cabal-version: 1.12
+name: slynx
+version: 0.0.1
+license: GPL-3
+license-file: LICENSE
+copyright: Dominik Schrempf (2019)
+maintainer: dominik.schrempf@gmail.com
+author: Dominik Schrempf
+homepage: https://github.com/dschrempf/elynx#readme
+bug-reports: https://github.com/dschrempf/elynx/issues
+synopsis: Handle molecular sequences
+description:
+    Examine, modify, and simulate molecular sequences in a reproducible way. Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
+category: Bioinformatics
+build-type: Simple
+extra-source-files:
+    README.md
+    ChangeLog.md
+
+source-repository head
+    type: git
+    location: https://github.com/dschrempf/elynx
+
+library
+    exposed-modules:
+        Concatenate.Concatenate
+        Concatenate.Options
+        Examine.Examine
+        Examine.Options
+        Filter.Filter
+        Filter.Options
+        Simulate.Options
+        Simulate.PhyloModel
+        Simulate.Simulate
+        SubSample.Options
+        SubSample.SubSample
+        Tools
+        Translate.Options
+        Translate.Translate
+    hs-source-dirs: src
+    other-modules:
+        Paths_slynx
+    default-language: Haskell2010
+    ghc-options: -Wall
+    build-depends:
+        async >=2.2.2 && <2.3,
+        base >=4.12.0.0 && <4.13,
+        bytestring >=0.10.8.2 && <0.11,
+        containers >=0.6.0.1 && <0.7,
+        data-memocombinators >=0.5.1 && <0.6,
+        elynx-seq >=0.0.1 && <0.1,
+        elynx-tools >=0.0.1 && <0.1,
+        elynx-tree >=0.0.1 && <0.1,
+        hmatrix >=0.20.0.0 && <0.21,
+        integration >=0.2.1 && <0.3,
+        lens >=4.17.1 && <4.18,
+        math-functions >=0.3.1.0 && <0.4,
+        matrices >=0.5.0 && <0.6,
+        megaparsec >=7.0.5 && <7.1,
+        monad-logger >=0.3.30 && <0.4,
+        mwc-random >=0.14.0.0 && <0.15,
+        optparse-applicative >=0.14.3.0 && <0.15,
+        parallel >=3.2.2.0 && <3.3,
+        primitive >=0.6.4.0 && <0.7,
+        statistics >=0.15.0.0 && <0.16,
+        text >=1.2.3.1 && <1.3,
+        transformers >=0.5.6.2 && <0.6,
+        vector >=0.12.0.3 && <0.13,
+        vector-th-unbox >=0.2.1.6 && <0.3,
+        word8 >=0.1.3 && <0.2
+
+executable slynx
+    main-is: Main.hs
+    hs-source-dirs: app
+    other-modules:
+        Options
+        Paths_slynx
+    default-language: Haskell2010
+    ghc-options: -Wall -eventlog -threaded -rtsopts -with-rtsopts=-N
+    build-depends:
+        async >=2.2.2 && <2.3,
+        base >=4.12.0.0 && <4.13,
+        bytestring >=0.10.8.2 && <0.11,
+        containers >=0.6.0.1 && <0.7,
+        data-memocombinators >=0.5.1 && <0.6,
+        elynx-seq >=0.0.1 && <0.1,
+        elynx-tools >=0.0.1 && <0.1,
+        hmatrix >=0.20.0.0 && <0.21,
+        integration >=0.2.1 && <0.3,
+        lens >=4.17.1 && <4.18,
+        math-functions >=0.3.1.0 && <0.4,
+        matrices >=0.5.0 && <0.6,
+        megaparsec >=7.0.5 && <7.1,
+        monad-logger >=0.3.30 && <0.4,
+        mwc-random >=0.14.0.0 && <0.15,
+        optparse-applicative >=0.14.3.0 && <0.15,
+        parallel >=3.2.2.0 && <3.3,
+        primitive >=0.6.4.0 && <0.7,
+        slynx -any,
+        statistics >=0.15.0.0 && <0.16,
+        text >=1.2.3.1 && <1.3,
+        transformers >=0.5.6.2 && <0.6,
+        vector >=0.12.0.3 && <0.13,
+        vector-th-unbox >=0.2.1.6 && <0.3,
+        word8 >=0.1.3 && <0.2
diff --git a/src/Concatenate/Concatenate.hs b/src/Concatenate/Concatenate.hs
new file mode 100644
--- /dev/null
+++ b/src/Concatenate/Concatenate.hs
@@ -0,0 +1,43 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Analyze.Analyze
+Description :  Parse sequence file formats and analyze them
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Oct  5 08:41:05 2018.
+
+-}
+
+module Concatenate.Concatenate
+  ( concatenateCmd
+  )
+where
+
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+
+import           Concatenate.Options
+import           Tools
+
+import           ELynx.Data.Sequence.Sequence
+import           ELynx.Export.Sequence.Fasta
+import           ELynx.Tools.InputOutput
+
+-- | Concatenate sequences.
+concatenateCmd :: Maybe FilePath -> Concatenate ()
+concatenateCmd outFileBaseName = do
+  $(logInfo) "Command: Concatenate sequences."
+  ConcatenateArguments al fps <- lift ask
+  sss <- mapM (readSeqs al . Just) fps
+  let result      = sequencesToFasta $ concatenateSeqs sss
+  let outFilePath = (++ ".fasta") <$> outFileBaseName
+  io "concatenated multi sequence alignment " result outFilePath
+
diff --git a/src/Concatenate/Options.hs b/src/Concatenate/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Concatenate/Options.hs
@@ -0,0 +1,47 @@
+{- |
+Module      :  Concatenate.Options
+Description :  ELynxSeq argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+-}
+
+module Concatenate.Options
+  ( ConcatenateArguments (..)
+  , Concatenate
+  , concatenateArguments
+  ) where
+
+import           Control.Applicative
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Options.Applicative
+
+import           Tools
+
+import           ELynx.Data.Alphabet.Alphabet
+
+-- | Arguments needed to concatenate multi sequence alignments.
+data ConcatenateArguments = ConcatenateArguments
+    { ccAlphabet :: Alphabet
+    , ccInFiles  :: [FilePath] }
+
+-- | Logger and Reader type.
+type Concatenate = LoggingT (ReaderT ConcatenateArguments IO)
+
+-- | Command line parser.
+concatenateArguments :: Parser ConcatenateArguments
+concatenateArguments = ConcatenateArguments
+               <$> alphabetOpt
+               <*> some inFileArg
+
+inFileArg :: Parser FilePath
+inFileArg = strArgument $
+  metavar "INPUT-FILE" <>
+  help "Read sequences from INPUT-FILE"
diff --git a/src/Examine/Examine.hs b/src/Examine/Examine.hs
new file mode 100644
--- /dev/null
+++ b/src/Examine/Examine.hs
@@ -0,0 +1,106 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+
+Module      :  Analyze.Analyze
+Description :  Parse sequence file formats and analyze them
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Oct  5 08:41:05 2018.
+
+-}
+
+module Examine.Examine
+  ( examineCmd
+  )
+  where
+
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+import qualified Data.ByteString.Lazy.Char8                 as L
+import           Text.Printf
+
+import           Examine.Options
+import           Tools
+
+import           ELynx.Data.Sequence.MultiSequenceAlignment
+import           ELynx.Data.Sequence.Sequence
+import           ELynx.Tools.InputOutput
+
+examineMSA :: Bool -> MultiSequenceAlignment -> L.ByteString
+examineMSA perSiteFlag msa =
+  L.unlines [ L.pack $ "Total number of columns in alignment: "
+              ++ show (msaLength msa)
+            , L.pack $ "Number of columns without gaps: "
+              ++ show (msaLength msaNoGaps)
+            , L.pack $ "Number of columns with standard characters only: "
+              ++ show (msaLength msaOnlyStd)
+            , L.empty
+            , L.pack $ "Total number of characters: " ++ show nTot
+            , L.pack $ "Standard (i.e., not extended IUPAC) characters: "
+              ++ show (nTot - nIUPAC - nGaps - nUnknowns)
+            , L.pack $ "Extended IUPAC characters: " ++ show nIUPAC
+            , L.pack $ "Gaps: " ++ show nGaps
+            , L.pack $ "Unknowns: " ++ show nUnknowns
+            , L.pack $ "Percentage of standard characters: "
+              ++ printf "%.3f" (1.0 - percentageIUPAC - percentageGaps - percentageUnknowns)
+            , L.pack $ "Percentage of extended IUPAC characters: "
+              ++ printf "%.3f" percentageIUPAC
+            , L.pack $ "Percentage of gaps: "
+              ++ printf "%.3f" percentageGaps
+            , L.pack $ "Percentage of unknowns: "
+              ++ printf "%.3f" percentageUnknowns
+            , L.empty
+            , L.pack "Mean effective number of states (measured using entropy):"
+            , L.pack "Across whole alignment: "
+              <> L.pack (printf "%.3f" kEffMean)
+            , L.pack "Across columns without gaps: "
+              <> L.pack (printf "%.3f" kEffMeanNoGaps)
+            , L.pack "Across columns without extended IUPAC characters: "
+              <> L.pack (printf "%.3f" kEffMeanOnlyStd)
+            ]
+  <> perSiteBS
+  where
+    nTot                = msaLength msa * msaNSequences msa
+    nIUPAC              = countIUPACChars msa
+    nGaps               = countGaps msa
+    nUnknowns           = countUnknowns msa
+    percentageIUPAC     = fromIntegral nIUPAC    / fromIntegral nTot :: Double
+    percentageGaps      = fromIntegral nGaps     / fromIntegral nTot :: Double
+    percentageUnknowns  = fromIntegral nUnknowns / fromIntegral nTot :: Double
+    msaNoGaps           = filterColumnsNoGaps msa
+    msaOnlyStd          = filterColumnsOnlyStd msaNoGaps
+    kEffs               = kEffEntropy . toFrequencyData $ msa
+    kEffsNoGaps         = kEffEntropy . toFrequencyData $ msaNoGaps
+    kEffsOnlyStd        = kEffEntropy . toFrequencyData $ msaOnlyStd
+    kEffMean            = sum kEffs / fromIntegral (length kEffs)
+    kEffMeanNoGaps      = sum kEffsNoGaps  / fromIntegral (length kEffsNoGaps)
+    kEffMeanOnlyStd     = sum kEffsOnlyStd / fromIntegral (length kEffsOnlyStd)
+    perSiteBS           = if perSiteFlag
+                          then L.unlines [ L.pack "Effective number of used states per site:"
+                                         , L.pack . show $ kEffs
+                                         ]
+                          else L.empty
+
+examine :: Bool -> [Sequence] -> L.ByteString
+examine perSiteFlag ss = summarizeSequenceList ss <>
+  case fromSequenceList ss of
+    Left _    -> L.empty
+    Right msa -> L.pack "\n" <> examineMSA perSiteFlag msa
+
+-- | Examine sequences.
+examineCmd :: Maybe FilePath -> Examine ()
+examineCmd outFileBaseName = do
+  $(logInfo) "Command: Examine sequences."
+  ExamineArguments al inFile perSiteFlag <- lift ask
+  ss <- readSeqs al inFile
+  let result = examine perSiteFlag ss
+  let outFilePath = (++ ".out") <$> outFileBaseName
+  io "result of examination" result outFilePath
diff --git a/src/Examine/Options.hs b/src/Examine/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Examine/Options.hs
@@ -0,0 +1,54 @@
+{- |
+Module      :  Examine.Options
+Description :  ELynxSeq argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+-}
+
+module Examine.Options
+  ( ExamineArguments (..)
+  , Examine
+  , examineArguments
+  ) where
+
+import           Control.Applicative
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Options.Applicative
+
+import           Tools
+
+import           ELynx.Data.Alphabet.Alphabet
+
+-- | Arguments needed to examine sequences.
+data ExamineArguments = ExamineArguments
+    { exAlphabet :: Alphabet
+    , exInFile   :: Maybe FilePath
+    , exPerSite  :: Bool }
+
+-- | Logger and Reader type.
+type Examine = LoggingT (ReaderT ExamineArguments IO)
+
+-- | Command line parser.
+examineArguments :: Parser ExamineArguments
+examineArguments = ExamineArguments
+           <$> alphabetOpt
+           <*> optional filePathArg
+           <*> examinePerSiteOpt
+
+examinePerSiteOpt :: Parser Bool
+examinePerSiteOpt = switch $
+  long "per-site" <>
+  help "Report per site summary statistics"
+
+filePathArg :: Parser FilePath
+filePathArg = strArgument $
+  metavar "INPUT-FILE" <>
+  help "Read sequences from INPUT-FILE"
diff --git a/src/Filter/Filter.hs b/src/Filter/Filter.hs
new file mode 100644
--- /dev/null
+++ b/src/Filter/Filter.hs
@@ -0,0 +1,76 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Analyze.Analyze
+Description :  Parse sequence file formats and analyze them
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Oct  5 08:41:05 2018.
+
+-}
+
+module Filter.Filter
+  ( filterRowsCmd
+  , filterColumnsCmd
+  )
+  where
+
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+import qualified Data.ByteString.Lazy.Char8                 as L
+import           Data.Maybe                                 (fromMaybe)
+import qualified Data.Text                                  as T
+
+import           Filter.Options
+import           Tools
+
+import           ELynx.Data.Sequence.MultiSequenceAlignment
+import           ELynx.Data.Sequence.Sequence
+import           ELynx.Export.Sequence.Fasta
+import           ELynx.Tools.InputOutput
+import           ELynx.Tools.Misc
+
+filterRows :: Maybe Int -> Maybe Int -> [Sequence] -> L.ByteString
+filterRows ml ms ss = sequencesToFasta $ compose filters ss
+  where filters = map (fromMaybe id) [filterLongerThan <$> ml, filterShorterThan <$> ms]
+
+-- | Filter sequences.
+filterRowsCmd :: Maybe FilePath -> FilterRows ()
+filterRowsCmd outFileBaseName = do
+  $(logInfo) "Command: Filter sequences of a list of sequences."
+  FilterRowsArguments al inFile long short <- lift ask
+  maybe (return ())
+    (\val -> $(logInfo) $ T.pack $ "  Keep sequences longer than " <> show val <> ".") long
+  maybe (return ())
+    (\val -> $(logInfo) $ T.pack $ "  Keep sequences shorter than " <> show val <> ".") short
+  ss <- readSeqs al inFile
+  let result      = filterRows long short ss
+  let outFilePath = (++ ".fasta") <$> outFileBaseName
+  io "filtered sequences" result outFilePath
+
+filterColumns :: Maybe Double -> [Sequence] -> L.ByteString
+filterColumns ms ss = sequencesToFasta . toSequenceList $ compose filters msa
+  where msa = either error id (fromSequenceList ss)
+        filters = map (fromMaybe id) [ filterColumnsStd <$> ms ]
+
+-- | Filter columns.
+filterColumnsCmd :: Maybe FilePath -> FilterColumns ()
+filterColumnsCmd outFileBaseName = do
+  $(logInfo) "Command: Filter columns of a multi sequence alignment."
+  FilterColumnsArguments al inFile standard <- lift ask
+  case standard of
+    Nothing -> return ()
+    Just p -> $(logInfo) $ T.pack $
+        "  Keep columns with a proportion of standard (non-IUPAC) characters larger than "
+        ++ show p ++ "."
+  ss <- readSeqs al inFile
+  let result      = filterColumns standard ss
+  let outFilePath = (++ ".fasta") <$> outFileBaseName
+  io "filtered sequences" result outFilePath
diff --git a/src/Filter/Options.hs b/src/Filter/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Filter/Options.hs
@@ -0,0 +1,88 @@
+{- |
+Module      :  Filter.Options
+Description :  ELynxSeq argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+-}
+
+module Filter.Options
+  ( FilterRowsArguments (..)
+  , FilterColumnsArguments (..)
+  , FilterRows
+  , FilterColumns
+  , filterRowsArguments
+  , filterColumnsArguments
+  ) where
+
+import           Control.Applicative
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Options.Applicative
+
+import           Tools
+
+import           ELynx.Data.Alphabet.Alphabet
+
+-- | Arguments needed for filtering sequences.
+data FilterRowsArguments = FilterRowsArguments
+  { frAlphabet :: Alphabet
+  , frInFile   :: Maybe FilePath
+  , frLonger   :: Maybe Int
+  , frShorter  :: Maybe Int }
+
+-- | Arguments needed for filtering columns of a multi sequence alignment.
+data FilterColumnsArguments = FilterColumnsArguments
+  { fcAlphabet :: Alphabet
+  , fcInFile   :: Maybe FilePath
+  , fcStandard :: Maybe Double }
+
+-- | Logger and Reader for sequence filtering.
+type FilterRows = LoggingT (ReaderT FilterRowsArguments IO)
+
+-- | Logger and Reader for column filtering.
+type FilterColumns = LoggingT (ReaderT FilterColumnsArguments IO)
+
+-- | Command line parser.
+filterRowsArguments :: Parser FilterRowsArguments
+filterRowsArguments = FilterRowsArguments
+              <$> alphabetOpt
+              <*> optional inFileArg
+              <*> filterLongerThanOpt
+              <*> filterShorterThanOpt
+
+filterLongerThanOpt :: Parser (Maybe Int)
+filterLongerThanOpt = optional $ option auto $
+  long "longer-than" <>
+  metavar "LENGTH" <>
+  help "Only keep sequences longer than LENGTH"
+
+filterShorterThanOpt :: Parser (Maybe Int)
+filterShorterThanOpt = optional $ option auto $
+  long "shorter-than" <>
+  metavar "LENGTH" <>
+  help "Only keep sequences shorter than LENGTH"
+
+-- | Command line parser.
+filterColumnsArguments :: Parser FilterColumnsArguments
+filterColumnsArguments = FilterColumnsArguments
+                 <$> alphabetOpt
+                 <*> optional inFileArg
+                 <*> filterStandardOpt
+
+filterStandardOpt :: Parser (Maybe Double)
+filterStandardOpt = optional $ option auto $
+  long "standard-chars" <>
+  metavar "DOUBLE" <>
+  help "Keep columns with a proportion standard (non-IUPAC) characters larger than DOUBLE in [0,1]"
+
+inFileArg :: Parser FilePath
+inFileArg = strArgument $
+  metavar "INPUT-FILE" <>
+  help "Read sequences from INPUT-FILE"
diff --git a/src/Simulate/Options.hs b/src/Simulate/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Simulate/Options.hs
@@ -0,0 +1,168 @@
+{- |
+Module      :  Simulate.Options
+Description :  ELynxSim argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+Available options:
+  -h,--help                Show this help text
+  -v,--version             Show version
+  -t,--tree-file NAME      Specify tree file NAME
+  -s,--substitution-model MODEL
+                           Set the phylogenetic substitution model; available
+                           models are shown below
+  -m,--mixture-model MODEL Set the phylogenetic mixture model; available models
+                           are shown below
+  -l,--length NUMBER       Set alignment length to NUMBER
+  -e,--edm-file NAME       empirical distribution model file NAME in Phylobayes
+                           format
+  -w,--mixture-model-weights [DOUBLE,DOUBLE,...]
+                           weights of mixture model components
+  -g,--gamma-rate-heterogeneity (NCAT, SHAPE)
+                           number of gamma rate categories and shape parameter
+  -e,--seed [INT]            Set seed for the random number generator; list of 32
+                           bit integers with up to 256 elements (default: [0])
+  -q,--quiet               Be quiet
+  -o,--output-file NAME    Specify output file NAME
+
+
+-}
+
+
+module Simulate.Options
+  ( GammaRateHeterogeneityParams
+  , SimulateArguments (..)
+  , Simulate
+  , simulateArguments
+  , simulateFooter
+  ) where
+
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Data.List
+import           Data.Word
+import           Options.Applicative
+
+import           ELynx.Tools.Options
+
+-- | Number of gamma rate categories and alpha parameter.
+type GammaRateHeterogeneityParams = (Int, Double)
+
+-- | Arguments needed to simulate sequences.
+data SimulateArguments = SimulateArguments
+  { argsTreeFile                :: FilePath
+  , argsSubstitutionModelString :: Maybe String
+  , argsMixtureModelString      :: Maybe String
+  , argsEDMFile                 :: Maybe FilePath
+  , argsMixtureWeights          :: Maybe [Double]
+  , argsGammaParams             :: Maybe GammaRateHeterogeneityParams
+  , argsLength                  :: Int
+  , argsMaybeSeed               :: Maybe [Word32]
+  }
+
+-- | A simulation can log stuff and read the necessary arguments.
+type Simulate = LoggingT (ReaderT SimulateArguments IO)
+
+-- | Sub command parser.
+simulateArguments :: Parser SimulateArguments
+simulateArguments = SimulateArguments
+  <$> treeFileOpt
+  <*> phyloSubstitutionModelOpt
+  <*> phyloMixtureModelOpt
+  <*> maybeEDMFileOpt
+  <*> maybeMixtureWeights
+  <*> maybeGammaParams
+  <*> lengthOpt
+  <*> seedOpt
+
+treeFileOpt :: Parser FilePath
+treeFileOpt = strOption $
+  long "tree-file"
+  <> short 't'
+  <> metavar "Name"
+  <> help "Read trees from file NAME"
+
+phyloSubstitutionModelOpt :: Parser (Maybe String)
+phyloSubstitutionModelOpt = optional $ strOption $
+  long "substitution-model"
+  <> short 's'
+  <> metavar "MODEL"
+  <> help "Set the phylogenetic substitution model; available models are shown below (mutually exclusive with -m option)"
+
+phyloMixtureModelOpt :: Parser (Maybe String)
+phyloMixtureModelOpt = optional $ strOption
+  ( long "mixture-model"
+    <> short 'm'
+    <> metavar "MODEL"
+    <> help "Set the phylogenetic mixture model; available models are shown below (mutually exclusive with -s option)" )
+
+maybeEDMFileOpt :: Parser (Maybe FilePath)
+maybeEDMFileOpt = optional $ strOption
+  ( long "edm-file"
+    <> short 'e'
+    <> metavar "NAME"
+    <> help "Empirical distribution model file NAME in Phylobayes format" )
+
+maybeMixtureWeights :: Parser (Maybe [Double])
+maybeMixtureWeights = optional $ option auto
+  ( long "mixture-model-weights"
+    <> short 'w'
+    <> metavar "\"[DOUBLE,DOUBLE,...]\""
+    <> help "Weights of mixture model components" )
+
+maybeGammaParams :: Parser (Maybe GammaRateHeterogeneityParams)
+maybeGammaParams = optional $ option auto
+  ( long "gamma-rate-heterogeneity"
+    <> short 'g'
+    <> metavar "\"(NCAT,SHAPE)\""
+    <> help "Number of gamma rate categories and shape parameter" )
+
+lengthOpt :: Parser Int
+lengthOpt = option auto
+  ( long "length"
+    <> short 'l'
+    <> metavar "NUMBER"
+    <> help "Set alignment length to NUMBER" )
+
+-- | The model specification is somewhat complicated, so we need to provide
+-- additional help.
+simulateFooter :: String
+simulateFooter = intercalate "\n" $ sms ++ mms
+  where
+    sms =
+      [ "Substitution models:"
+      , "-s \"MODEL[PARAMETER,PARAMETER,...]{STATIONARY_DISTRIBUTION}\""
+      , "   Supported DNA models: JC, HKY."
+      , "     For example,"
+      , "       -s HKY[KAPPA]{DOUBLE,DOUBLE,DOUBLE,DOUBLE}"
+      , "   Supported Protein models: Poisson, Poisson-Custom, LG, LG-Custom, WAG, WAG-Custom."
+      , "     MODEL-Custom means that only the exchangeabilities of MODEL are used,"
+      , "     and a custom stationary distribution is provided."
+      , "     For example,"
+      , "       -s LG-Custom{...}"
+      ]
+    mms =
+      [ ""
+      , "Mixture models:"
+      , "-m \"MIXTURE(SUBSTITUTION_MODEL_1,SUBSTITUTION_MODEL_2)\""
+      , "   For example,"
+      , "     -m \"MIXTURE(JC,HKY[6.0]{0.3,0.2,0.2,0.3})\""
+      , "Mixture weights have to be provided with the -w option."
+      , ""
+      , "Special mixture models:"
+      , "-m CXX"
+      , "   where XX is 10, 20, 30, 40, 50, or 60; CXX models, Quang et al., 2008."
+      , "-m \"EDM(EXCHANGEABILITIES)\""
+      , "   Arbitrary empirical distribution mixture (EDM) models."
+      , "   Stationary distributions have to be provided with the -e option."
+      , "   For example,"
+      , "     LG exchangeabilities with stationary distributions given in FILE."
+      , "     -m \"EDM(LG-Custom)\" -e FILE"
+      , "For special mixture models, mixture weights are optional."
+      ]
diff --git a/src/Simulate/PhyloModel.hs b/src/Simulate/PhyloModel.hs
new file mode 100644
--- /dev/null
+++ b/src/Simulate/PhyloModel.hs
@@ -0,0 +1,188 @@
+{- |
+Module      :  Simulate.PhyloModel
+Description :  Parse and interpret the model string
+Copyright   :  (c) Dominik Schrempf 2019
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Feb  1 13:32:16 2019.
+
+-}
+
+module Simulate.PhyloModel
+  ( getPhyloModel
+  ) where
+
+import qualified Data.ByteString.Lazy.Char8                    as L
+import           Data.Maybe
+import           Data.Void
+import           Data.Word                                     (Word8)
+import           Numeric.LinearAlgebra                         (norm_1, size,
+                                                                vector)
+import           Text.Megaparsec
+import           Text.Megaparsec.Byte
+import           Text.Megaparsec.Byte.Lexer
+
+import           ELynx.Data.MarkovProcess.AminoAcid
+import           ELynx.Data.MarkovProcess.CXXModels
+import qualified ELynx.Data.MarkovProcess.MixtureModel         as M
+import           ELynx.Data.MarkovProcess.Nucleotide
+import qualified ELynx.Data.MarkovProcess.PhyloModel           as P
+import           ELynx.Data.MarkovProcess.RateMatrix
+import qualified ELynx.Data.MarkovProcess.SubstitutionModel    as S
+import           ELynx.Import.MarkovProcess.EDMModelPhylobayes (EDMComponent)
+import           ELynx.Tools.ByteString
+import           ELynx.Tools.Equality
+import           ELynx.Tools.InputOutput
+
+type Parser = Parsec Void L.ByteString
+
+bs :: String -> L.ByteString
+bs = L.pack
+
+nNuc :: Int
+-- nNuc = length (alphabet :: [Nucleotide])
+nNuc = 4
+
+nAA :: Int
+-- nAA = length (alphabet :: [AminoAcid])
+nAA = 20
+
+-- Model parameters between square brackets.
+paramsStart :: Word8
+paramsStart = c2w '['
+
+paramsEnd :: Word8
+paramsEnd = c2w ']'
+
+-- Stationary distribution between curly brackets.
+sdStart :: Word8
+sdStart = c2w '{'
+
+sdEnd :: Word8
+sdEnd = c2w '}'
+
+-- Mixture model components between round brackets.
+mmStart :: Word8
+mmStart = c2w '('
+
+mmEnd :: Word8
+mmEnd = c2w ')'
+
+separator :: Word8
+separator = c2w ','
+
+name :: Parser String
+name = L.unpack <$>
+  takeWhile1P (Just "Model name") (`notElem` [paramsStart, paramsEnd, sdStart, sdEnd, mmStart, mmEnd, separator])
+
+params :: Parser [Double]
+params = between (char paramsStart) (char paramsEnd) (sepBy1 float (char separator))
+
+stationaryDistribution :: Parser StationaryDistribution
+stationaryDistribution = do
+  f <- vector <$> between (char sdStart) (char sdEnd) (sepBy1 float (char separator))
+  if nearlyEq (norm_1 f) 1.0
+    then return f
+    else error $ "Sum of stationary distribution is " ++ show (norm_1 f)
+         ++ " but should be 1.0."
+
+assertLength :: StationaryDistribution -> Int -> a -> a
+assertLength d n r = if size d /= n
+                    then error $ "Length of stationary distribution is " ++ show (size d)
+                         ++ " but should be " ++ show n ++ "."
+                    else r
+
+-- This is the main function that connects the model string, the parameters and
+-- the stationary distribution. It should check that the model is valid.
+assembleSubstitutionModel :: String -> Maybe S.Params -> Maybe StationaryDistribution
+                          -> Either String S.SubstitutionModel
+-- DNA models.
+assembleSubstitutionModel "JC" Nothing Nothing = Right jc
+assembleSubstitutionModel "HKY" (Just [k]) (Just d) = Right $ assertLength d nNuc $ hky k d
+-- Protein models.
+assembleSubstitutionModel "LG" Nothing Nothing = Right lg
+assembleSubstitutionModel "LG-Custom" Nothing (Just d) = Right $ assertLength d nAA $ lgCustom Nothing d
+assembleSubstitutionModel "WAG" Nothing Nothing = Right wag
+assembleSubstitutionModel "WAG-Custom" Nothing (Just d) = Right $ assertLength d nAA $ wagCustom Nothing d
+assembleSubstitutionModel "Poisson" Nothing Nothing = Right poisson
+assembleSubstitutionModel "Poisson-Custom" Nothing (Just d) = Right $ assertLength d nAA $ poissonCustom Nothing d
+-- Ohterwisse, we cannot assemble the model.
+assembleSubstitutionModel n mps mf = Left $ unlines
+  [ "Cannot assemble substitution model. "
+  , "Name: " ++ show n
+  , "Parameters: " ++ show mps
+  , "Stationary distribution: " ++ show mf ]
+
+parseSubstitutionModel :: Parser S.SubstitutionModel
+parseSubstitutionModel = do
+  n  <- name
+  mps <- optional params
+  mf <- optional stationaryDistribution
+  let esm = assembleSubstitutionModel n mps mf
+  case esm of
+    Left err -> fail err
+    Right sm -> return sm
+
+edmModel :: [EDMComponent] -> Maybe [M.Weight] -> Parser M.MixtureModel
+edmModel cs mws = do
+  _ <- chunk (bs "EDM")
+  _ <- char mmStart
+  n <- name
+  mps <- optional params
+  _ <- char mmEnd
+  let sms     = map (\c -> assembleSubstitutionModel n mps (Just $ snd c)) cs
+      edmName = "EDM" ++ show (length cs)
+      ws      = fromMaybe (map fst cs) mws
+      errs    = [ e | (Left e) <- sms ]
+  if not $ null errs
+  then fail $ head errs
+  else return $ M.MixtureModel edmName
+    [ M.Component w sm | (w, Right sm) <- zip ws sms ]
+
+cxxModel :: Maybe [M.Weight] -> Parser M.MixtureModel
+cxxModel mws = do
+  _ <- char (c2w 'C')
+  n <- decimal :: Parser Int
+  case cxx n mws of
+    Nothing -> fail "Only 10, 20, 30, 40, 50, and 60 components are supported."
+    Just m -> return m
+
+standardMixtureModel :: [M.Weight] -> Parser M.MixtureModel
+standardMixtureModel ws = do
+  _ <- chunk (bs "MIXTURE")
+  _ <- char mmStart
+  sms <- parseSubstitutionModel `sepBy1` char separator
+  _ <- char mmEnd
+  return $ M.MixtureModel "MIXTURE"
+    [ M.Component w sm | (w, sm) <- zip ws sms]
+
+mixtureModel :: Maybe [EDMComponent] -> Maybe [M.Weight] -> Parser M.MixtureModel
+mixtureModel Nothing   Nothing       = try (cxxModel Nothing) <|> fail "No weights provided."
+mixtureModel Nothing   mws@(Just ws) = try (cxxModel mws) <|> standardMixtureModel ws
+mixtureModel (Just cs) mws           = edmModel cs mws
+
+-- | Parse the phylogenetic model string. The argument list is somewhat long,
+-- but models can have many parameters and we have to check for redundant
+-- parameters.
+--
+-- @
+-- getPhyloModel maybeSubstitutionModelString maybeMixtureModelString maybeEDMComponents
+-- @
+getPhyloModel :: Maybe String -> Maybe String -> Maybe [M.Weight] -> Maybe [EDMComponent]
+              -> Either String P.PhyloModel
+getPhyloModel Nothing Nothing _ _ =
+  Left "No model was given. See help."
+getPhyloModel (Just _) (Just _) _ _ =
+  Left "Both, substitution and mixture model string given; use only one."
+getPhyloModel (Just s) Nothing Nothing Nothing =
+  Right $ P.SubstitutionModel $ parseStringWith "Substitution model string" parseSubstitutionModel s
+getPhyloModel (Just _) Nothing (Just _) _ =
+  Left "Weights given; but cannot be used with substitution model."
+getPhyloModel (Just _) Nothing _ (Just _) =
+  Left "Empirical distribution mixture model components given; but cannot be used with substitution model."
+getPhyloModel Nothing (Just m) mws mcs =
+  Right $ P.MixtureModel $ parseStringWith "Mixture model string" (mixtureModel mcs mws) m
diff --git a/src/Simulate/Simulate.hs b/src/Simulate/Simulate.hs
new file mode 100644
--- /dev/null
+++ b/src/Simulate/Simulate.hs
@@ -0,0 +1,158 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Simulate.Simulate
+Description :  Simulate multiple sequence alignments
+Copyright   :  (c) Dominik Schrempf 2019
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Mon Jan 28 14:12:52 2019.
+
+-}
+
+module Simulate.Simulate
+  ( simulateCmd )
+where
+
+import           Control.Concurrent
+import           Control.Concurrent.Async
+import           Control.Lens
+import           Control.Monad.IO.Class
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+import qualified Data.ByteString.Lazy                            as L
+import qualified Data.ByteString.Lazy.Char8                      as LC
+import qualified Data.Set                                        as Set
+import qualified Data.Text                                       as T
+import qualified Data.Text.Lazy                                  as LT
+import qualified Data.Text.Lazy.Encoding                         as LT
+import           Data.Tree
+import qualified Data.Vector.Unboxed                             as V
+import           Numeric.LinearAlgebra                           hiding ((<>))
+import           System.Random.MWC
+
+import           Simulate.Options
+import           Simulate.PhyloModel
+
+import           ELynx.Data.Alphabet.Alphabet                    as A
+import           ELynx.Data.MarkovProcess.GammaRateHeterogeneity
+import qualified ELynx.Data.MarkovProcess.MixtureModel           as M
+import qualified ELynx.Data.MarkovProcess.PhyloModel             as P
+import qualified ELynx.Data.MarkovProcess.SubstitutionModel      as S
+import           ELynx.Data.Sequence.MultiSequenceAlignment
+import           ELynx.Data.Sequence.Sequence                    hiding (name)
+import           ELynx.Data.Tree.MeasurableTree
+import           ELynx.Data.Tree.NamedTree
+import           ELynx.Data.Tree.Tree
+import           ELynx.Export.Sequence.Fasta
+import           ELynx.Import.MarkovProcess.EDMModelPhylobayes   hiding (Parser)
+import           ELynx.Import.Tree.Newick                        hiding (name)
+import           ELynx.Simulate.MarkovProcessAlongTree
+
+import           ELynx.Tools.ByteString
+import           ELynx.Tools.Concurrent
+import           ELynx.Tools.InputOutput
+import           ELynx.Tools.Misc
+
+-- Simulate a 'MultiSequenceAlignment' for a given phylogenetic model,
+-- phylogenetic tree, and alignment length.
+simulateMSA :: (Measurable a, Named a)
+            => P.PhyloModel -> Tree a -> Int -> GenIO
+            -> IO MultiSequenceAlignment
+simulateMSA pm t n g = do
+  c  <- getNumCapabilities
+  gs <- splitGen c g
+  let chunks = getChunks c n
+  leafStatesS <- case pm of
+    P.SubstitutionModel sm -> mapConcurrently
+      (\(num, gen) -> simulateAndFlattenNSitesAlongTree num d e t gen) (zip chunks gs)
+      where d = sm ^. S.stationaryDistribution
+            e = sm ^. S.exchangeabilityMatrix
+    P.MixtureModel mm      -> mapConcurrently
+      (\(num, gen) -> simulateAndFlattenNSitesAlongTreeMixtureModel num ws ds es t gen) (zip chunks gs)
+      where
+        ws = vector $ M.getWeights mm
+        ds = map (view S.stationaryDistribution) $ M.getSubstitutionModels mm
+        es = map (view S.exchangeabilityMatrix) $ M.getSubstitutionModels mm
+  -- XXX: The horizontal concatenation might be slow. If so, 'concatenateSeqs'
+  -- or 'concatenateMSAs' can be used, which directly appends vectors.
+  let leafStates = horizontalConcat leafStatesS
+      leafNames  = map getName $ leaves t
+      code       = P.getAlphabet pm
+      -- XXX: Probably use type safe stuff here?
+      alph       = A.all $ alphabetSpec code
+      sequences  = [ Sequence sName code (V.fromList $ map (`Set.elemAt` alph) ss) |
+                    (sName, ss) <- zip leafNames leafStates ]
+  return $ either error id $ fromSequenceList sequences
+
+-- Summarize EDM components; line to be printed to screen or log.
+summarizeEDMComponents :: [EDMComponent] -> L.ByteString
+summarizeEDMComponents cs = LC.pack
+                            $ "Empiricial distribution mixture model with "
+                            ++ show (length cs) ++ " components."
+
+-- XXX. Maybe provide human readable model file. But then, why is this
+-- necessary. A human readable summary is reported anyways, and for Protein
+-- models the exchangeabilities are too many.
+reportModel :: Maybe FilePath -> P.PhyloModel -> Simulate ()
+reportModel outFn m = do
+  let modelFn = (<> ".model") <$> outFn
+  io "model definition (machine readable)" (bsShow m <> "\n") modelFn
+
+-- | Simulate sequences.
+simulateCmd :: Maybe FilePath -> Simulate ()
+simulateCmd outFn = do
+  a <- lift ask
+  $(logInfo) "Read tree."
+  let treeFile = argsTreeFile a
+  tree <- liftIO $ parseFileWith newick treeFile
+  $(logInfo) $ LT.toStrict $ LT.decodeUtf8 $ summarize tree
+
+  let edmFile = argsEDMFile a
+  edmCs <- case edmFile of
+    Nothing   -> return Nothing
+    Just edmF -> do
+      $(logInfo) "Read EDM file."
+      liftIO $ Just <$> parseFileWith phylobayes edmF
+  maybe (return ()) ($(logInfo) . LT.toStrict . LT.decodeUtf8 . summarizeEDMComponents) edmCs
+
+  $(logInfo) "Read model string."
+  let ms = argsSubstitutionModelString a
+      mm = argsMixtureModelString a
+      mws = argsMixtureWeights a
+      eitherPhyloModel' = getPhyloModel ms mm mws edmCs
+  phyloModel' <- case eitherPhyloModel' of
+    Left err -> lift $ error err
+    Right pm -> return pm
+
+  let maybeGammaParams = argsGammaParams a
+  phyloModel <- case maybeGammaParams of
+    Nothing         -> do
+      $(logInfo) $ LT.toStrict $ LT.decodeUtf8
+        $ LC.unlines $ P.summarize phyloModel'
+      return phyloModel'
+    Just (n, alpha) -> do
+      $(logInfo) $ LT.toStrict $ LT.decodeUtf8
+        $ LC.unlines $ P.summarize phyloModel' ++ summarizeGammaRateHeterogeneity n alpha
+      return $ expand n alpha phyloModel'
+  reportModel outFn phyloModel
+
+  $(logInfo) "Simulate alignment."
+  let alignmentLength = argsLength a
+  $(logInfo) $ T.pack $ "Length: " <> show alignmentLength <> "."
+  let maybeSeed = argsMaybeSeed a
+  gen <- case maybeSeed of
+    Nothing -> $(logInfo) "Seed: random"
+               >> liftIO createSystemRandom
+    Just s  -> $(logInfo) (T.pack ("Seed: " <> show s <> "."))
+               >> liftIO (initialize (V.fromList s))
+  msa <- liftIO $ simulateMSA phyloModel tree alignmentLength gen
+  let output = (sequencesToFasta . toSequenceList) msa
+      outFile = (<> ".fasta") <$> outFn
+  io "simulated multi sequence alignment" output outFile
diff --git a/src/SubSample/Options.hs b/src/SubSample/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/SubSample/Options.hs
@@ -0,0 +1,69 @@
+{- |
+Module      :  SubSample.Options
+Description :  ELynxSeq argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+-}
+
+module SubSample.Options
+  ( SubSampleArguments (..)
+  , SubSample
+  , subSampleArguments
+  ) where
+
+import           Control.Applicative
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Data.Word
+import           Options.Applicative
+
+import           Tools
+
+import           ELynx.Data.Alphabet.Alphabet
+import           ELynx.Tools.Options
+
+-- | Data structure holding the Command line arguments.
+data SubSampleArguments = SubSampleArguments
+    { ssAlphabet    :: Alphabet
+    , ssInFile      :: Maybe FilePath
+    , ssNSites      :: Int
+    , ssNAlignments :: Int
+    , ssMbSeed      :: Maybe [Word32] }
+
+-- | The sub sample command can log stuff and read necessary arguments.
+type SubSample = LoggingT (ReaderT SubSampleArguments IO)
+
+-- | Sub command parser.
+subSampleArguments :: Parser SubSampleArguments
+subSampleArguments = SubSampleArguments
+                     <$> alphabetOpt
+                     <*> optional filePathArg
+                     <*> subSampleNSitesOpt
+                     <*> subSampleNAlignmentsOpt
+                     <*> seedOpt
+
+subSampleNSitesOpt :: Parser Int
+subSampleNSitesOpt = option auto $
+  long "number-of-sites" <>
+  short 'n' <>
+  metavar "INT" <>
+  help "Number of sites randomly drawn with replacement"
+
+subSampleNAlignmentsOpt :: Parser Int
+subSampleNAlignmentsOpt = option auto $
+  long "number-of-alignments" <>
+  short 'm' <>
+  metavar "INT" <>
+  help "Number of multi sequence alignments to be created"
+
+filePathArg :: Parser FilePath
+filePathArg = strArgument $
+  metavar "INPUT-FILE" <>
+  help "Read sequences from INPUT-FILE"
diff --git a/src/SubSample/SubSample.hs b/src/SubSample/SubSample.hs
new file mode 100644
--- /dev/null
+++ b/src/SubSample/SubSample.hs
@@ -0,0 +1,70 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Analyze.Analyze
+Description :  Parse sequence file formats and analyze them
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Oct  5 08:41:05 2018.
+
+-}
+
+module SubSample.SubSample
+  ( subSampleCmd
+  )
+where
+
+import           Control.Monad
+import           Control.Monad.IO.Class
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+import qualified Data.Text                                  as T
+import qualified Data.Text.Lazy                             as LT
+import qualified Data.Text.Lazy.Builder                     as LT
+import qualified Data.Text.Lazy.Builder.Int                 as LT
+import qualified Data.Vector                                as V
+import           System.Random.MWC
+
+import           SubSample.Options
+import           Tools
+
+import           ELynx.Data.Sequence.MultiSequenceAlignment
+import           ELynx.Export.Sequence.Fasta
+import           ELynx.Tools.InputOutput
+
+-- | Get a given number of output file names with provided suffix.
+--
+-- > getOutFilePaths "BasePath" 11 "fasta"
+--
+-- Will result in @BasePath.00.fasta@ up to @BasePath.10.fasta@.
+getOutFilePaths :: String -> Int -> String -> [FilePath]
+getOutFilePaths file n suffix = [ file ++ "." ++ digitStr i ++ "." ++ suffix
+                                | i <- [0 .. n-1] ]
+  where nDigits    = ceiling $ logBase (10 :: Double) (fromIntegral n)
+        digitStr i = T.unpack $ T.justifyRight nDigits '0' (LT.toStrict $ LT.toLazyText $ LT.decimal i)
+
+-- | Sub sample sequences.
+subSampleCmd :: Maybe FilePath  -- ^ Output file base name
+             -> SubSample ()
+subSampleCmd outFileBaseName = do
+  SubSampleArguments al inFile nSites nAlignments seed <- lift ask
+  $(logInfo) "Command: Sub sample from a multi sequence alignment."
+  $(logInfo) $ T.pack $ "  Sample " <> show nSites <> " sites."
+  $(logInfo) $ T.pack $ "  Sample " <> show nAlignments <> " multi sequence alignments."
+  ss <- readSeqs al inFile
+  gen <- liftIO $ maybe createSystemRandom (initialize . V.fromList) seed
+  let msa = either error id (fromSequenceList ss)
+  samples <- lift $ replicateM nAlignments $ randomSubSample nSites msa gen
+  let results = map (sequencesToFasta . toSequenceList) samples
+  outFilePaths <- case outFileBaseName of
+    Nothing -> return $ repeat Nothing
+    Just fn -> return $ Just <$> getOutFilePaths fn nAlignments "fasta"
+  zipWithM_ (io "sub sampled multi sequence alignments") results outFilePaths
+
diff --git a/src/Tools.hs b/src/Tools.hs
new file mode 100644
--- /dev/null
+++ b/src/Tools.hs
@@ -0,0 +1,53 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Tools
+Description :  Common tools for sequence lynx
+Copyright   :  (c) Dominik Schrempf 2019
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sat Sep  7 06:24:22 2019.
+
+-}
+
+module Tools
+  ( -- * Tools
+    readSeqs
+    -- * Options
+  , alphabetOpt
+  ) where
+
+import           Control.Monad.IO.Class
+import           Control.Monad.Logger
+import qualified Data.Text                    as T
+import           Options.Applicative
+
+import           ELynx.Data.Alphabet.Alphabet
+import           ELynx.Data.Sequence.Sequence
+import           ELynx.Import.Sequence.Fasta
+import           ELynx.Tools.InputOutput
+
+-- | Read sequences of given alphabet from file or standard input.
+readSeqs :: (MonadIO m, MonadLogger m) => Alphabet -> Maybe FilePath -> m [Sequence]
+readSeqs a mfp = do
+  case mfp of
+    Nothing -> $(logInfo) $ T.pack
+               $ "Read sequences from standard input; alphabet "
+               <> show a <> "."
+    Just fp -> $(logInfo) $ T.pack
+               $ "Read sequences from file "
+               <> fp <> "; alphabet" <> show a <> "."
+  liftIO $ parseFileOrIOWith (fasta a) mfp
+
+-- | Command line option to specify the alphabet. Used by various commands.
+alphabetOpt :: Parser Alphabet
+alphabetOpt = option auto $
+  long "alphabet" <>
+  short 'a' <>
+  metavar "NAME" <>
+  help "Specify alphabet type NAME"
diff --git a/src/Translate/Options.hs b/src/Translate/Options.hs
new file mode 100644
--- /dev/null
+++ b/src/Translate/Options.hs
@@ -0,0 +1,71 @@
+{- |
+Module      :  Translate.Options
+Description :  ELynxSeq argument parsing
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Sun Oct  7 17:29:45 2018.
+
+-}
+
+module Translate.Options
+  ( TranslateArguments (..)
+  , Translate
+  , translateArguments
+  ) where
+
+import           Control.Applicative
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Reader
+import           Data.List
+import           Options.Applicative
+
+import           Tools
+
+import           ELynx.Data.Alphabet.Alphabet
+import           ELynx.Data.Character.Codon
+import           ELynx.Tools.Misc
+
+-- | Arguments needed to translate sequences.
+data TranslateArguments = TranslateArguments
+    { trAlphabet      :: Alphabet
+    , trInFile        :: Maybe FilePath
+    , trReadingFrame  :: Int
+    , trUniversalCode :: UniversalCode }
+
+-- | Logger and Reader type.
+type Translate = LoggingT (ReaderT TranslateArguments IO)
+
+-- | Command line parser.
+translateArguments :: Parser TranslateArguments
+translateArguments = TranslateArguments <$>
+                     alphabetOpt <*>
+                     optional inFileArg <*>
+                     readingFrameOpt <*>
+                     universalCodeOpt
+
+readingFrameOpt :: Parser Int
+readingFrameOpt = option auto $
+  long "reading-frame" <>
+  short 'r' <>
+  metavar "INT" <>
+  help "Reading frame [0|1|2]."
+
+universalCodeOpt :: Parser UniversalCode
+universalCodeOpt = option auto $
+  long "universal-code" <>
+  short 'u' <>
+  metavar "CODE" <>
+  help ("universal code; one of: " ++ codeStr ++ ".")
+  where codes = allValues :: [UniversalCode]
+        codeWords = map show codes
+        codeStr = intercalate ", " codeWords
+
+inFileArg :: Parser FilePath
+inFileArg = strArgument $
+  metavar "INPUT-FILE" <>
+  help "Read sequences from INPUT-FILE"
diff --git a/src/Translate/Translate.hs b/src/Translate/Translate.hs
new file mode 100644
--- /dev/null
+++ b/src/Translate/Translate.hs
@@ -0,0 +1,51 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TemplateHaskell   #-}
+
+{- |
+Module      :  Analyze.Analyze
+Description :  Parse sequence file formats and analyze them
+Copyright   :  (c) Dominik Schrempf 2018
+License     :  GPL-3
+
+Maintainer  :  dominik.schrempf@gmail.com
+Stability   :  unstable
+Portability :  portable
+
+Creation date: Fri Oct  5 08:41:05 2018.
+
+-}
+
+module Translate.Translate
+  ( translateCmd
+  )
+  where
+
+import           Control.Monad.Logger
+import           Control.Monad.Trans.Class
+import           Control.Monad.Trans.Reader
+import qualified Data.Text                     as T
+
+import           Tools
+import           Translate.Options
+
+import           ELynx.Data.Character.Codon
+import           ELynx.Data.Sequence.Sequence
+import           ELynx.Data.Sequence.Translate
+import           ELynx.Export.Sequence.Fasta
+import           ELynx.Tools.InputOutput
+
+translateSeqs :: Int -> UniversalCode -> [Sequence] -> [Sequence]
+translateSeqs rf uc = map (translateSeq uc rf)
+
+-- | Translate sequences.
+translateCmd :: Maybe FilePath -> Translate ()
+translateCmd outFileBaseName = do
+  $(logInfo) "Command: Translate sequences to amino acids."
+  TranslateArguments al inFile rf uc <- lift ask
+  $(logInfo) $ T.pack $ "  Universal code: " <> show uc <> "."
+  $(logInfo) $ T.pack $ "  Reading frame: " <> show rf <> "."
+  $(logInfo) ""
+  ss <- readSeqs al inFile
+  let result      = sequencesToFasta $ translateSeqs rf uc ss
+  let outFilePath = (++ ".fasta") <$> outFileBaseName
+  io "translated sequences" result outFilePath
