diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -5,6 +5,16 @@
 ## Unreleased changes
 
 
+## Version 0.5.0
+
+-   `modLen`, `modSup`.
+-   Newtype wrappers for branch length, branch support, and node name. Those data
+    types and some functions were also renamed.
+-   Add `Path`, and `getSubTreeUnsafe` to tree zipper.
+-   Rename `unsafe` functions so that `unsafe` is at the end.
+-   Many small changes.
+
+
 ## Version 0.4.1
 
 -   Improve `TimeSpec` (Point process).
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 # The ELynx Suite
 
-Version: 0.4.1.
+Version: 0.5.0.
 Reproducible evolution made easy.
 
 <p align="center"><img src="https://travis-ci.org/dschrempf/elynx.svg?branch=master"/></p>
@@ -90,9 +90,9 @@
 
     slynx --help | head -n -16
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] 
                  [-f|--force] [--no-elynx-file] COMMAND
@@ -137,9 +137,9 @@
 
     slynx concatenate --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx concatenate (-a|--alphabet NAME) INPUT-FILE
       Concatenate sequences found in input files.
@@ -158,9 +158,9 @@
 
     slynx examine --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx examine (-a|--alphabet NAME) INPUT-FILE [--per-site]
       Examine sequences. If data is a multi sequence alignment, additionally analyze columns.
@@ -180,9 +180,9 @@
 
     slynx filter-rows --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx filter-rows (-a|--alphabet NAME) INPUT-FILE [--longer-than LENGTH] 
                              [--shorter-than LENGTH] [--standard-characters]
@@ -203,9 +203,9 @@
 
     slynx filter-columns --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx filter-columns (-a|--alphabet NAME) INPUT-FILE 
                                 [--standard-chars DOUBLE]
@@ -227,9 +227,9 @@
 
     slynx simulate --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx simulate (-t|--tree-file Name) [-s|--substitution-model MODEL] 
                           [-m|--mixture-model MODEL] [-e|--edm-file NAME] 
@@ -306,9 +306,9 @@
 
     slynx sub-sample --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx sub-sample (-a|--alphabet NAME) INPUT-FILE
                             (-n|--number-of-sites INT)
@@ -336,9 +336,9 @@
 
     slynx translate --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: slynx translate (-a|--alphabet NAME) INPUT-FILE (-r|--reading-frame INT)
                            (-u|--universal-code CODE)
@@ -361,9 +361,9 @@
 
     tlynx --help | head -n -16
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: tlynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME] 
                  [-f|--force] [--no-elynx-file] COMMAND
@@ -401,9 +401,9 @@
 
     tlynx compare --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: tlynx compare [-n|--normalize] [-b|--bipartitions] [-t|--intersect] 
                          [-f|--newick-format FORMAT] NAMES
@@ -430,9 +430,9 @@
 
     tlynx examine --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: tlynx examine INPUT-FILE [-f|--newick-format FORMAT]
       Compute summary statistics of phylogenetic trees.
@@ -454,9 +454,9 @@
 
     tlynx simulate --help
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: tlynx simulate (-t|--nTrees INT) (-n|--nLeaves INT) PROCESS 
                           [-u|--sub-sample DOUBLE] [-s|--summary-statistics] 
@@ -491,9 +491,9 @@
 
     elynx --help | head -n -16
 
-    ELynx Suite version 0.4.1.
+    ELynx Suite version 0.5.0.
     Developed by Dominik Schrempf.
-    Compiled on October 16, 2020, at 12:46 pm, UTC.
+    Compiled on November 10, 2020, at 14:29 pm, UTC.
     
     Usage: elynx COMMAND
       Validate and redo past ELynx analyses
diff --git a/src/TLynx/Compare/Compare.hs b/src/TLynx/Compare/Compare.hs
--- a/src/TLynx/Compare/Compare.hs
+++ b/src/TLynx/Compare/Compare.hs
@@ -21,7 +21,6 @@
 import Control.Monad.IO.Class
 import Control.Monad.Logger
 import Control.Monad.Trans.Reader (ask)
-import qualified Data.ByteString.Char8 as BS
 import qualified Data.ByteString.Lazy.Char8 as BL
 import Data.List (intercalate)
 import qualified Data.Map as M
@@ -46,7 +45,7 @@
   FilePath ->
   ELynx
     CompareArguments
-    (Tree Phylo BS.ByteString, Tree Phylo BS.ByteString)
+    (Tree Phylo Name, Tree Phylo Name)
 treesOneFile tf = do
   nwF <- argsNewickFormat . local <$> ask
   $(logInfo) $ T.pack $ "Parse file '" ++ tf ++ "'."
@@ -63,7 +62,7 @@
   FilePath ->
   ELynx
     CompareArguments
-    (Tree Phylo BS.ByteString, Tree Phylo BS.ByteString)
+    (Tree Phylo Name, Tree Phylo Name)
 treesTwoFiles tf1 tf2 = do
   nwF <- argsNewickFormat . local <$> ask
   $(logInfo) $ T.pack $ "Parse first tree file '" ++ tf1 ++ "'."
@@ -112,8 +111,8 @@
 
 analyzeDistance ::
   Handle ->
-  Tree Phylo BS.ByteString ->
-  Tree Phylo BS.ByteString ->
+  Tree Phylo Name ->
+  Tree Phylo Name ->
   ELynx CompareArguments ()
 analyzeDistance outH t1 t2 = do
   let formatD str val = T.justifyLeft 25 ' ' str <> "  " <> val
@@ -178,8 +177,8 @@
 
 analyzeBipartitions ::
   Handle ->
-  Tree Phylo BS.ByteString ->
-  Tree Phylo BS.ByteString ->
+  Tree Phylo Name ->
+  Tree Phylo Name ->
   ELynx CompareArguments ()
 analyzeBipartitions outH t1 t2 =
   case (phyloToLengthTree t1, phyloToLengthTree t2) of
@@ -215,8 +214,8 @@
           liftIO $ hPutStrLn outH "There are no common bipartitions."
           liftIO $ hPutStrLn outH "No plots have been generated."
         else do
-          let bpToBrLen1 = M.map getLen $ either error id $ bipartitionToBranch t1l
-              bpToBrLen2 = M.map getLen $ either error id $ bipartitionToBranch t2l
+          let bpToBrLen1 = M.map (fromLength . getLen) $ either error id $ bipartitionToBranch t1l
+              bpToBrLen2 = M.map (fromLength . getLen) $ either error id $ bipartitionToBranch t2l
           liftIO $
             hPutStrLn
               outH
diff --git a/src/TLynx/Connect/Connect.hs b/src/TLynx/Connect/Connect.hs
--- a/src/TLynx/Connect/Connect.hs
+++ b/src/TLynx/Connect/Connect.hs
@@ -20,7 +20,6 @@
 import Control.Monad.IO.Class
 import Control.Monad.Logger
 import Control.Monad.Trans.Reader (ask)
-import qualified Data.ByteString.Char8 as BS
 import qualified Data.ByteString.Lazy.Char8 as BL
 import qualified Data.Set as S
 import ELynx.Tools
@@ -68,9 +67,9 @@
   liftIO $ hClose outH
 
 connectTrees ::
-  Tree Length BS.ByteString ->
-  Tree Length BS.ByteString ->
-  Forest Length BS.ByteString
+  Tree Length Name ->
+  Tree Length Name ->
+  Forest Length Name
 connectTrees t = either error id . connect 0 "root" t
 
 type Constraint a = S.Set a
@@ -103,7 +102,7 @@
   FilePath ->
   ELynx
     ConnectArguments
-    (Tree Length BS.ByteString, Tree Length BS.ByteString)
+    (Tree Length Name, Tree Length Name)
 parseTreeTuple l r = do
   nwF <- nwFormat . local <$> ask
   tl <- liftIO $ parseTree nwF l
@@ -130,7 +129,7 @@
   $(logInfo) $ fromBs $ BL.intercalate "\n" $ map toNewick cts
   (tl, tr) <- parseTreeTuple l r
   let ts = connectTrees tl tr
-      cs = map S.fromList $ concatMap multifurcatingGroups cts :: [Constraint BS.ByteString]
+      cs = map S.fromList $ concatMap multifurcatingGroups cts :: [Constraint Name]
       -- Only collect trees that are compatible with the constraints.
       ts' = filter (compatibleWith getName cs) ts
   $(logInfo) $ "Connected  trees: " <> tShow (length ts)
diff --git a/src/TLynx/Distance/Distance.hs b/src/TLynx/Distance/Distance.hs
--- a/src/TLynx/Distance/Distance.hs
+++ b/src/TLynx/Distance/Distance.hs
@@ -31,7 +31,6 @@
 import Control.Monad.Trans.Class
 import Control.Monad.Trans.Reader hiding (local)
 import Data.Bifunctor
-import qualified Data.ByteString.Char8 as BS
 import qualified Data.ByteString.Lazy.Char8 as BL
 import Data.List hiding (intersect)
 import Data.Maybe
@@ -136,17 +135,20 @@
             ++ "."
     BranchScore -> $(logInfo) "Use branch score distance."
   let distanceMeasure' ::
-        Tree Phylo BS.ByteString ->
-        Tree Phylo BS.ByteString ->
+        Tree Phylo Name ->
+        Tree Phylo Name ->
         Double
       distanceMeasure' t1 t2 = either error id $ case dist of
         Symmetric -> second fromIntegral $ symmetric t1 t2
-        IncompatibleSplit val -> second fromIntegral $ incompatibleSplits
-                                 (collapse val $ normalizeBranchSupport $ either error id $ phyloToSupportTree t1)
-                                 (collapse val $ normalizeBranchSupport $ either error id $ phyloToSupportTree t2)
+        IncompatibleSplit val ->
+          second fromIntegral $
+            incompatibleSplits
+              (collapse val $ normalizeBranchSupport $ either error id $ phyloToSupportTree t1)
+              (collapse val $ normalizeBranchSupport $ either error id $ phyloToSupportTree t2)
         BranchScore ->
           branchScore (normalizeF $ either error id $ phyloToLengthTree t1) (normalizeF $ either error id $ phyloToLengthTree t2)
-        where normalizeF = if argsNormalize l then normalizeBranchLengths else id
+        where
+          normalizeF = if argsNormalize l then normalizeBranchLengths else id
   -- Possibly intersect trees before distance calculation.
   when (argsIntersect l) $
     $(logInfo) "Intersect trees before calculation of distances."
diff --git a/src/TLynx/Distance/Options.hs b/src/TLynx/Distance/Options.hs
--- a/src/TLynx/Distance/Options.hs
+++ b/src/TLynx/Distance/Options.hs
@@ -23,6 +23,7 @@
 import qualified Data.Attoparsec.ByteString.Char8 as AC
 import qualified Data.ByteString.Char8 as BS
 import ELynx.Tools
+import ELynx.Tree (Support (..), toSupportUnsafe)
 import Options.Applicative
 import TLynx.Parsers
 import Text.Printf
@@ -33,7 +34,7 @@
     Symmetric
   | -- | Incompatible split distance; collapse nodes
     -- with branch support below given value.
-    IncompatibleSplit Double
+    IncompatibleSplit Support
   | -- | Branch score distance.
     BranchScore
   deriving (Eq, Generic)
@@ -44,7 +45,7 @@
 
 instance Show DistanceMeasure where
   show Symmetric = "Symmetric"
-  show (IncompatibleSplit c) = "Incompatible Split (" ++ printf "%.2f" c ++ ")"
+  show (IncompatibleSplit c) = "Incompatible Split (" ++ printf "%.2f" (fromSupport c) ++ ")"
   show BranchScore = "Branch Score"
 
 -- | Arguments needed to compute distance measures.
@@ -117,7 +118,7 @@
   _ <- AC.char ']'
   _ <- AC.endOfInput
   if (0 <= f) && (f <= 1)
-    then pure $ IncompatibleSplit f
+    then pure $ IncompatibleSplit $ toSupportUnsafe f
     else error "Branch support has to be in [0, 1]."
 
 branchScore :: AC.Parser DistanceMeasure
diff --git a/src/TLynx/Examine/Examine.hs b/src/TLynx/Examine/Examine.hs
--- a/src/TLynx/Examine/Examine.hs
+++ b/src/TLynx/Examine/Examine.hs
@@ -20,7 +20,6 @@
 import Control.Monad.IO.Class
 import Control.Monad.Logger
 import Control.Monad.Trans.Reader (ask)
-import qualified Data.ByteString.Char8 as BS
 import qualified Data.ByteString.Lazy.Char8 as BL
 import Data.Containers.ListUtils (nubOrd)
 import Data.List ((\\))
@@ -35,8 +34,8 @@
 import TLynx.Parsers
 import Text.Printf
 
-pretty :: BranchLength -> String
-pretty = printf "%.5f"
+pretty :: Length -> String
+pretty = printf "%.5f" . fromLength
 
 prettyRow :: String -> String -> BL.ByteString
 prettyRow name val = alignLeft 33 n <> alignRight 8 v
@@ -45,8 +44,8 @@
     v = BL.pack val
 
 -- | Examine branches of a tree.
-summarizeBranchLengths :: Measurable e => Tree e a -> BL.ByteString
-summarizeBranchLengths t =
+summarizeLengths :: Measurable e => Tree e a -> BL.ByteString
+summarizeLengths t =
   BL.intercalate
     "\n"
     [ prettyRow "Origin height: " $ pretty h,
@@ -59,7 +58,7 @@
     h' = sum (distancesOriginLeaves t) / fromIntegral n
     b = totalBranchLength t
 
-readTrees :: FilePath -> ELynx ExamineArguments (Forest Phylo BS.ByteString)
+readTrees :: FilePath -> ELynx ExamineArguments (Forest Phylo Name)
 readTrees fp = do
   $(logInfo) $ T.pack $ "Read tree(s) from file " <> fp <> "."
   nf <- argsNewickFormat . local <$> ask
@@ -71,7 +70,7 @@
   let l = phyloToLengthTree t
   case l of
     Left _ -> hPutStrLn h "Branch lengths not available."
-    Right t' -> BL.hPutStrLn h $ summarizeBranchLengths t'
+    Right t' -> BL.hPutStrLn h $ summarizeLengths t'
   unless (null dups) $
     hPutStrLn h ""
       >> hPutStrLn
@@ -79,7 +78,7 @@
         ("Duplicate leaves: " ++ show dups)
   BL.hPutStrLn h $ "Leave names: " <> BL.intercalate " " lvs
   where
-    lvs = map getName $ leaves t
+    lvs = map (fromName . getName) $ leaves t
     dups = lvs \\ nubOrd lvs
 
 -- | Examine phylogenetic trees.
diff --git a/src/TLynx/Parsers.hs b/src/TLynx/Parsers.hs
--- a/src/TLynx/Parsers.hs
+++ b/src/TLynx/Parsers.hs
@@ -19,7 +19,6 @@
   )
 where
 
-import qualified Data.ByteString.Char8 as BS
 import Data.List
 import ELynx.Tools
 import ELynx.Tree
@@ -35,7 +34,7 @@
 --
 -- Error if no or more than one trees are found.
 -- Error if both file formats fail to parse.
-parseTree :: NewickFormat -> FilePath -> IO (Tree Phylo BS.ByteString)
+parseTree :: NewickFormat -> FilePath -> IO (Tree Phylo Name)
 parseTree fmt fn = do
   parseResultNewick <- runParserOnFile (oneNewick fmt) fn
   case parseResultNewick of
@@ -51,7 +50,7 @@
 -- | Parse a Newick tree file or a Nexus file with Newick trees.
 --
 -- Error if both file formats fail to parse.
-parseTrees :: NewickFormat -> FilePath -> IO (Forest Phylo BS.ByteString)
+parseTrees :: NewickFormat -> FilePath -> IO (Forest Phylo Name)
 parseTrees fmt fn = do
   parseResultNewick <- runParserOnFile (someNewick fmt) fn
   case parseResultNewick of
diff --git a/src/TLynx/Shuffle/Shuffle.hs b/src/TLynx/Shuffle/Shuffle.hs
--- a/src/TLynx/Shuffle/Shuffle.hs
+++ b/src/TLynx/Shuffle/Shuffle.hs
@@ -54,10 +54,10 @@
   let dh = sum $ map (height t -) (distancesOriginLeaves t)
   $(logDebug) $ "Distance in branch length to being ultrametric: " <> tShow dh
   when (dh > 2e-4) (error "Tree is not ultrametric.")
-  when (dh > eps && dh < 2e-4) $
+  when (dh > toLengthUnsafe eps && dh < 2e-4) $
     $(logInfo)
       "Tree is nearly ultrametric, ignore branch length differences smaller than 2e-4."
-  when (dh < eps) $ $(logInfo) "Tree is ultrametric."
+  when (dh < toLengthUnsafe eps) $ $(logInfo) "Tree is ultrametric."
   let cs = filter (> 0) $ labels $ C.extend rootHeight t
       ls = map getName $ leaves t
   $(logDebug) $ "Number of coalescent times: " <> tShow (length cs)
@@ -73,11 +73,11 @@
 
 shuffleT ::
   Int -> -- How many?
-  Double -> -- Stem length.
-  [Double] -> -- Coalescent times.
-  [BL.ByteString] -> -- Leave names.
+  Length -> -- Stem length.
+  [Length] -> -- Coalescent times.
+  [Name] -> -- Leave names.
   GenIO ->
-  IO (Forest Length BL.ByteString)
+  IO (Forest Length Name)
 shuffleT n o cs ls gen = do
   css <- grabble cs n (length cs) gen
   lss <- grabble ls n (length ls) gen
diff --git a/src/TLynx/Simulate/Simulate.hs b/src/TLynx/Simulate/Simulate.hs
--- a/src/TLynx/Simulate/Simulate.hs
+++ b/src/TLynx/Simulate/Simulate.hs
@@ -209,10 +209,10 @@
     return [dropLeavesWith (`Set.notMember` ls) tree | ls <- lsSets]
 
 -- Pair of branch length with number of extant children.
-type BrLnNChildren = (BranchLength, Int)
+type BrLnNChildren = (Length, Int)
 
 -- Possible summary statistic of phylogenetic trees. A list of tuples
--- (BranchLength, NumberOfExtantChildrenBelowThisBranch).
+-- (Length, NumberOfExtantChildrenBelowThisBranch).
 type NChildSumStat = [BrLnNChildren]
 
 -- Format the summary statistics in the following form:
@@ -228,7 +228,7 @@
 
 formatNChildSumStatLine :: BrLnNChildren -> BB.Builder
 formatNChildSumStatLine (l, n) =
-  BB.intDec n <> BB.char8 ' ' <> BB.doubleDec l <> BB.char8 '\n'
+  BB.intDec n <> BB.char8 ' ' <> BB.doubleDec (fromLength l) <> BB.char8 '\n'
 
 -- Compute NChilSumStat for a phylogenetic tree.
 toNChildSumStat :: Measurable e => Tree e a -> NChildSumStat
diff --git a/tlynx.cabal b/tlynx.cabal
--- a/tlynx.cabal
+++ b/tlynx.cabal
@@ -1,6 +1,6 @@
 cabal-version:  2.2
 name:           tlynx
-version:        0.4.1
+version:        0.5.0
 synopsis:       Handle phylogenetic trees
 description:    Examine, compare, and simulate phylogenetic trees in a reproducible way. Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
 category:       Bioinformatics