diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -5,6 +5,16 @@
 ## Unreleased changes
 
 
+## Version 0.6.0.0
+
+-   **elynx-tree:** remove parallel folds with layers (`parBranchFoldMapWithLayer`
+    too special and slow).
+-   **elynx-tree:** fix various tree instances; add zip trees with appropriate
+    instances.
+-   Remove `monad-logger` dependency and implement lighter alternative.
+-   Significant changes to the tool chain.
+
+
 ## Version 0.5.1.0
 
 -   **elynx-tree:** new functions `isValidPath`, `isLeaf`, `depth`; add conversion
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 # The ELynx Suite
 
-Version: 0.5.1.0.
+Version: 0.6.0.0.
 Reproducible evolution made easy.
 
 <p align="center"><img src="https://travis-ci.org/dschrempf/elynx.svg?branch=master"/></p>
@@ -39,7 +39,7 @@
 
 # Installation
 
-ELynx is written in [Haskell](https://www.haskell.org/) and can be installed with [Stack](https://docs.haskellstack.org/en/stable/README/).
+ELynx is written in [Haskell](https://www.haskell.org/) and can be installed with [cabal-install](https://cabal.readthedocs.io/en/3.4/cabal-commands.html) or [Stack](https://docs.haskellstack.org/en/stable/README/).
 
 1.  Install Stack with your package manager, or directly from the web
     page.
@@ -67,15 +67,15 @@
     [PATH](https://en.wikipedia.org/wiki/PATH_(variable)) environment variable. Then, they can be used directly.
 
 
-# SLynx
+# Get help
 
-Handle evolutionary sequences.
+For example:
 
-    stack exec slynx -- --help | head -n -16
+    slynx --help
 
-    ELynx Suite version 0.5.1.0.
+    ELynx Suite version 0.6.0.0.
     Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
+    Compiled on September 3, 2021, at 20:56 pm, UTC.
     
     Usage: slynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] 
                  [-f|--force] [--no-elynx-file] COMMAND
@@ -84,7 +84,7 @@
     Available options:
       -h,--help                Show this help text
       -V,--version             Show version
-      -v,--verbosity VALUE     Be verbose; one of: Quiet Warning Info Debug
+      -v,--verbosity VALUE     Be verbose; one of: Quiet Warn Info Debug
                                (default: Info)
       -o,--output-file-basename NAME
                                Specify base name of output file
@@ -112,107 +112,33 @@
       - Protein (amino acids)
       - ProteinX (amino acids; including gaps)
       - ProteinS (amino acids; including gaps, and translation stops)
-
-
-## Concatenate
-
-Concatenate multi sequence alignments.
-
-    stack exec slynx -- concatenate --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: slynx concatenate (-a|--alphabet NAME) INPUT-FILE
-      Concatenate sequences found in input files.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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`.
-
-    stack exec slynx -- examine --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: slynx examine (-a|--alphabet NAME) INPUT-FILE [--per-site]
-      Examine sequences. If data is a multi sequence alignment, additionally analyze columns.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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`.
-
-    stack exec slynx -- filter-rows --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: slynx filter-rows (-a|--alphabet NAME) INPUT-FILE [--longer-than LENGTH] 
-                             [--shorter-than LENGTH] [--standard-characters]
-      Filter rows (or sequences) found in input files.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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
-      --standard-characters    Only keep sequences containing at least one standard
-                               (i.e., non-IUPAC) character
-      -h,--help                Show this help text
-
-Filter columns of multi sequence alignments with `filter-columns`.
-
-    stack exec slynx -- filter-columns --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
+      - ProteinI (amino acids; including gaps, translation stops, and IUPAC codes)
+    ELynx
+    -----
+    A Haskell library and tool set for computational biology. The goal of ELynx is
+    reproducible research. Evolutionary sequences and phylogenetic trees can be
+    read, viewed, modified and simulated. The command line with all arguments is
+    logged consistently, and automatically. Data integrity is verified using SHA256
+    sums so that validation of past analyses is possible without the need to
+    recompute the result.
     
-    Usage: slynx filter-columns (-a|--alphabet NAME) INPUT-FILE 
-                                [--standard-chars DOUBLE]
-      Filter columns of multi sequence alignments.
+    slynx     Analyze, modify, and simulate evolutionary sequences.
+    tlynx     Analyze, modify, and simulate phylogenetic trees.
+    elynx     Validate and redo past analyses.
     
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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
+    Get help for sub commands:
+      slynx examine --help
 
 
-## Simulate
+## Sub command
 
-Simulate sequences with `slynx simulate`.
+The documentation of sub commands can be accessed separately:
 
-    stack exec slynx -- simulate --help
+    slynx simulate --help
 
-    ELynx Suite version 0.5.1.0.
+    ELynx Suite version 0.6.0.0.
     Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
+    Compiled on September 3, 2021, at 20:56 pm, UTC.
     
     Usage: slynx simulate (-t|--tree-file Name) [-s|--substitution-model MODEL] 
                           [-m|--mixture-model MODEL] [-e|--edm-file NAME] 
@@ -281,315 +207,4 @@
          LG exchangeabilities with site profiles (Phylobayes) given in FILES.
          -m "EDM(LG-Custom)" -p FILES
     For special mixture models, mixture weights are optional.
-
-
-## Sub-sample
-
-Sub-sample columns from multi sequence alignments.
-
-    stack exec slynx -- sub-sample --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: slynx sub-sample (-a|--alphabet NAME) INPUT-FILE
-                            (-n|--number-of-sites INT)
-                            (-m|--number-of-alignments INT) [-S|--seed [INT]]
-      Sub-sample columns from multi sequence alignments.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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
-    
-    Create a given number of multi sequence alignments, each of which contains a given number of random sites drawn from the original multi sequence alignment.
-
-
-## Translate
-
-Translate sequences.
-
-    stack exec slynx -- translate --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: slynx translate (-a|--alphabet NAME) INPUT-FILE (-r|--reading-frame INT)
-                           (-u|--universal-code CODE)
-      Translate from DNA to Protein or DNAX to ProteinX.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -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.
-
-    stack exec tlynx -- --help | head -n -16
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] 
-                 [-f|--force] [--no-elynx-file] 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
-      -f,--force               Ignore previous analysis and overwrite existing
-                               output files.
-      --no-elynx-file          Do not write data required to reproduce an analysis.
-    
-    Available commands:
-      compare                  Compare two phylogenetic trees (compute distances and branch-wise differences).
-      connect                  Connect two phylogenetic trees in all ways (possibly honoring constraints).
-      distance                 Compute distances between many phylogenetic trees.
-      examine                  Compute summary statistics of phylogenetic trees.
-      shuffle                  Shuffle a phylogenetic tree (keep coalescent times, but shuffle topology and leaves).
-      simulate                 Simulate phylogenetic trees using a birth and death or coalescent process.
-    
-    
-    Available tree file formats:
-      - Newick Standard: Branch support values are stored in square brackets after branch lengths.
-      - Newick IqTree:   Branch support values are stored as node names after the closing bracket of forests.
-      - Newick RevBayes: Key-value pairs is provided in square brackets after node names as well as branch lengths. XXX: Key value pairs are ignored at the moment.
-
-
-## Compare
-
-Compute distances between phylogenetic trees.
-
-    stack exec tlynx -- compare --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx compare [-n|--normalize] [-b|--bipartitions] [-t|--intersect] 
-                         [-f|--newick-format FORMAT] NAMES
-      Compare two phylogenetic trees (compute distances and branch-wise differences).
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -n,--normalize           Normalize trees before comparison
-      -b,--bipartitions        Print and plot common and missing bipartitions
-      -t,--intersect           Compare intersections; i.e., before comparison, drop
-                               leaves that are not present in the other tree
-      -f,--newick-format FORMAT
-                               Newick tree format: Standard, IqTree, or RevBayes;
-                               default: Standard; for detailed help, see 'tlynx
-                               --help'
-      NAMES                    Tree files
-      -h,--help                Show this help text
-
-
-## Connect
-
-Connect two phylogenetic tree in all ways (possibly honoring constraints).
-
-    stack exec tlynx -- connect --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx connect [-f|--newick-format FORMAT] [-c|--contraints CONSTRAINTS]
-                         TREE-FILE-A TREE-FILE-B
-      Connect two phylogenetic trees in all ways (possibly honoring constraints).
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -f,--newick-format FORMAT
-                               Newick tree format: Standard, IqTree, or RevBayes;
-                               default: Standard; for detailed help, see 'tlynx
-                               --help'
-      -c,--contraints CONSTRAINTS
-                               File containing one or more Newick trees to be used
-                               as constraints
-      TREE-FILE-A              File containing the first Newick tree
-      TREE-FILE-B              File containing the second Newick tree
-      -h,--help                Show this help text
-
-
-## Distancce
-
-Compute distances between many phylogenetic trees.
-
-    stack exec tlynx -- distance --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx distance (-d|--distance MEASURE) [-n|--normalize] [-t|--intersect] 
-                          [-s|--summary-statistics] 
-                          [-m|--master-tree-file MASTER-TREE-File] 
-                          [-f|--newick-format FORMAT] [INPUT-FILES]
-      Compute distances between many phylogenetic trees.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -d,--distance MEASURE    Type of distance to calculate (available distance
-                               measures are listed below)
-      -n,--normalize           Normalize trees before distance calculation; only
-                               affect distances depending on branch lengths
-      -t,--intersect           Compare intersections; i.e., before comparison, drop
-                               leaves that are not present in the other tree
-      -s,--summary-statistics  Report summary statistics only
-      -m,--master-tree-file MASTER-TREE-File
-                               Compare all trees to the tree in the master tree
-                               file.
-      -f,--newick-format FORMAT
-                               Newick tree format: Standard, IqTree, or RevBayes;
-                               default: Standard; for detailed help, see 'tlynx
-                               --help'
-      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
-    
-    Distance measures:
-      symmetric                Symmetric distance (Robinson-Foulds distance).
-      incompatible-split[VAL]  Incompatible split distance. Collapse branches with (normalized)
-                               support less than 0.0<=VAL<=1.0 before distance calculation;
-                               if, let's say, VAL>0.7, only well supported differences contribute
-                               to the total distance.
-      branch-score             Branch score distance.
-
-
-## Examine
-
-Compute summary statistics of phylogenetic trees.
-
-    stack exec tlynx -- examine --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx examine INPUT-FILE [-f|--newick-format FORMAT]
-      Compute summary statistics of phylogenetic trees.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      INPUT-FILE               Read trees from INPUT-FILE
-      -f,--newick-format FORMAT
-                               Newick tree format: Standard, IqTree, or RevBayes;
-                               default: Standard; for detailed help, see 'tlynx
-                               --help'
-      -h,--help                Show this help text
-
-
-## Shuffle
-
-Shuffle a phylogenetic tree (keep coalescent times, but shuffle topology and
-leaves).
-
-    stack exec tlynx -- shuffle --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx shuffle [-f|--newick-format FORMAT] [-n|--replicates N] TREE-FILE 
-                         [-S|--seed [INT]]
-      Shuffle a phylogenetic tree (keep coalescent times, but shuffle topology and leaves).
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -f,--newick-format FORMAT
-                               Newick tree format: Standard, IqTree, or RevBayes;
-                               default: Standard; for detailed help, see 'tlynx
-                               --help'
-      -n,--replicates N        Number of trees to generate
-      TREE-FILE                File containing a Newick tree
-      -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
-
-
-## Simulate
-
-Simulate phylogenetic trees using birth and death processes.
-
-    stack exec tlynx -- simulate --help
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: tlynx simulate (-t|--nTrees INT) (-n|--nLeaves INT) PROCESS 
-                          [-u|--sub-sample DOUBLE] [-s|--summary-statistics] 
-                          [-S|--seed [INT]]
-      Simulate phylogenetic trees using a birth and death or coalescent process.
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-      -t,--nTrees INT          Number of trees
-      -n,--nLeaves INT         Number of leaves per tree
-      -u,--sub-sample DOUBLE   Perform sub-sampling; see below.
-      -s,--summary-statistics  For each branch, print length and number of children
-      -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
-    
-    Available processes:
-      birthdeath               Birth and death process
-      coalescent               Coalescent process
-    
-    See, for example, 'tlynx simulate birthdeath --help'.
-    Sub-sample with probability p:
-      1. Simulate one big tree with n'=round(n/p), n'>=n, leaves;
-      2. Randomly sample sub-trees with n leaves.
-      (With p=1.0, the same tree is reported over and over again.)
-
-
-# ELynx
-
-Validate and (optionally) redo past ELynx analyses.
-
-    stack exec elynx -- --help | head -n -16
-
-    ELynx Suite version 0.5.1.0.
-    Developed by Dominik Schrempf.
-    Compiled on June 12, 2021, at 14:54 pm, UTC.
-    
-    Usage: elynx COMMAND
-      Validate and redo past ELynx analyses
-    
-    Available options:
-      -h,--help                Show this help text
-      -V,--version             Show version
-    
-    Available commands:
-      validate                 Validate an ELynx analysis
-      redo                     Redo an ELynx analysis
 
diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -174,8 +174,8 @@
 runRedo :: RedoArguments -> IO ()
 runRedo a = do
   let fp = rElynxFile a
-  let f = rForce a
-  when (f == Force False) $ do
+  let f = rExecutionMode a
+  when (f == Fail) $ do
     putStrLn "Validate ELynx reproduction file before reanalysis."
     putStrLn "Use the --force (-f) option to skip this test."
     runValidate (ValidateArguments fp)
@@ -190,12 +190,14 @@
       else return as
   withProgName (getELynxProgName repr) $ withArgs as' $ redo repr
 
-setForce :: Arguments a -> Arguments a
-setForce (Arguments g l) = Arguments g {forceReanalysis = Force True} l
+setExecutionMode :: Arguments a -> Arguments a
+setExecutionMode (Arguments g l) = Arguments g' l
+  where
+    g' = g {executionMode = Overwrite}
 
 redo :: AllReproductions -> IO ()
-redo (S x) = slynx $ setForce $ reproducible x
-redo (T x) = tlynx $ setForce $ reproducible x
+redo (S x) = slynx $ setExecutionMode $ reproducible x
+redo (T x) = tlynx $ setExecutionMode $ reproducible x
 
 main :: IO ()
 main = do
diff --git a/app/Options.hs b/app/Options.hs
--- a/app/Options.hs
+++ b/app/Options.hs
@@ -54,12 +54,12 @@
 
 data RedoArguments = RedoArguments
   { rElynxFile :: FilePath,
-    rForce :: Force
+    rExecutionMode :: ExecutionMode
   }
   deriving (Eq, Show, Generic)
 
 redoArguments :: Parser RedoArguments
-redoArguments = RedoArguments <$> inFileArg <*> forceOpt
+redoArguments = RedoArguments <$> inFileArg <*> executionModeOpt
 
 redoDsc :: [String]
 redoDsc = ["Redo an ELynx analysis"]
diff --git a/elynx.cabal b/elynx.cabal
--- a/elynx.cabal
+++ b/elynx.cabal
@@ -1,44 +1,41 @@
-cabal-version:      2.2
-name:               elynx
-version:            0.5.1.1
-license:            GPL-3.0-or-later
-license-file:       LICENSE
-copyright:          Dominik Schrempf (2021)
-maintainer:         dominik.schrempf@gmail.com
-author:             Dominik Schrempf
-homepage:           https://github.com/dschrempf/elynx#readme
-bug-reports:        https://github.com/dschrempf/elynx/issues
-synopsis:           Validate and (optionally) redo ELynx analyses
-description:
-    Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
+cabal-version:  2.2
+name:           elynx
+version:        0.6.0.0
+synopsis:       Validate and (optionally) redo ELynx analyses
+description:    Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
+category:       Bioinformatics
+homepage:       https://github.com/dschrempf/elynx#readme
+bug-reports:    https://github.com/dschrempf/elynx/issues
+author:         Dominik Schrempf
+maintainer:     dominik.schrempf@gmail.com
+copyright:      Dominik Schrempf (2021)
+license:        GPL-3.0-or-later
+license-file:   LICENSE
+build-type:     Simple
 
-category:           Bioinformatics
-build-type:         Simple
 extra-source-files:
     README.md
     ChangeLog.md
 
 source-repository head
-    type:     git
-    location: https://github.com/dschrempf/elynx
+  type: git
+  location: https://github.com/dschrempf/elynx
 
 executable elynx
-    main-is:          Main.hs
-    hs-source-dirs:   app
-    other-modules:
-        Options
-        Paths_elynx
-
-    autogen-modules:  Paths_elynx
-    default-language: Haskell2010
-    ghc-options:
-        -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
-
-    build-depends:
-        aeson >=1.5.6.0,
-        base >=4.7 && <5,
-        bytestring >=0.10.12.0,
-        elynx-tools >=0.5.1.1,
-        optparse-applicative >=0.16.1.0,
-        slynx >=0.5.1.1,
-        tlynx >=0.5.1.1
+  main-is: Main.hs
+  other-modules:
+      Options
+      Paths_elynx
+  autogen-modules:
+      Paths_elynx
+  hs-source-dirs: app
+  ghc-options: -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
+  build-depends:
+      aeson
+    , base >=4.7 && <5
+    , bytestring
+    , elynx-tools
+    , optparse-applicative
+    , slynx
+    , tlynx
+  default-language: Haskell2010
