Rebuilding WAR files in webapps directory

Question

This script cleans up destination directory and copies file into it with new name. Can this intent be expressed more cleanly with shelly?

main = shellyFailDir $ verbosely $ do
  escaping False $ rm_rf $ webapps </> "*"
  cp (m2repo
       </> groupPath
       </> artifact
       </> version
       </> (intercalate "-" [artifact, version] `append` ".war")
     ) $ webapps </> (finalName `append` ".war")
  echo "done"

Alternate take:

main = shellyFailDir $ verbosely $ do
  ls webapps >>= mapM_ rm_rf
  cp (m2repo <> groupPath <> (mconcat . map fromText $ [artifact, version, artifactFileName]))
     $ webapps <> fromText (finalName <> extension)
  echo "done"

artifactFileName = intercalate "-" [artifact, version] <> extension

Having (types match only second version because they help pick correct Monoid):

m2repo = ".m2/repository" :: FilePath
version = "1.0-SNAPSHOT" :: Text
webapps = "tomcat/webapps" :: FilePath
groupPath = "com/example" :: FilePath
artifact = "app" :: Text
finalName = artifact
extension = ".war" :: Text

Answer 1

I think your first version looks pretty slick. You could use a let-binding to do a little reordering and naming.

import Data.Monoid

main = shellyFailDir $ verbosely $ do
  escaping False $ rm_rf $ webapps </> "*"
  let sourceName = artifact <> "-" <> version <> ".war"
      source = m2repo </> groupPath </> artifact </> version </> sourceName
      destination = webapps </> finalName <> ".war"
  cp source destination
  echo "done"