file-command-qq is a simple quasiquoter for running system commands that take a filepath as an argument. For instance will return You can think of [s|echo $filename|] essentially converts into Here is another example All "file parts" start with a '$'. The '$' can be escaped by preceding it with a '\' There are the following options for "file parts" $path $root $directory $parent $filename $dirname $basename $ext Which correspond to the respective functions in https://hackage.haskell.org/package/system-filepath-0.4.6/docs/Filesystem-Path.html#g:1