https://twitter.com/phadej/status/480263674586988544

sort-osx-path.sh

# if we have haskell installed
command -v runhaskell > /dev/null 2>&1
if [ $? ]; then

# Embedded haskell
TMP=`mktemp /tmp/orderpath.XXXXXX`
cat > $TMP <<'EOF'
module Main where

import System.Environment (getEnvironment)
import Data.Function (on)
import Data.List.Split (splitOn)
import Data.List (intercalate, sortBy, isPrefixOf)

sortPath :: String -> String
sortPath = intercalate ":" . map snd . sortBy (compare `on` metric) . zip [0, 1 ..] . splitOn ":"
  where metric (i, p) = i + if "/usr/local" `isPrefixOf` p then 0 else 1000

defaultPath :: String
defaultPath = "/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"

main :: IO ()
main = do
  env <- getEnvironment
  putStrLn $ maybe defaultPath sortPath $ lookup "PATH" env

EOF

# Run, and if succeed assign new PATH
SORTEDPATH=`runhaskell $TMP`
if [ $? ]; then
	export PATH=$SORTEDPATH
fi

# cleanup
rm $TMP
fi

sortPATH.hs

module Main where

import System.Environment (getEnvironment)
import Data.Function (on)
import Data.List.Split (splitOn)
import Data.List (intercalate, sortBy, isPrefixOf)

sortPath :: String -> String
sortPath = intercalate ":" . map snd . sortBy (compare `on` metric) . zip [0, 1 ..] . splitOn ":"
  where metric (i, p) = i + if "/usr/local" `isPrefixOf` p then 0 else 1000

defaultPath :: String
defaultPath = "/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin"

main :: IO ()
main = do
  env <- getEnvironment
  putStrLn $ maybe defaultPath sortPath $ lookup "PATH" env