if findExecutable finds a file that matchs the argument, check if it is an executable

[iago]

When search finds a file that matchs with the fileName argument of findExecutable, it doesn't check if the file is an executable file.

 do
  path <- getEnv "PATH"
  search (splitSearchPath path)
  where
    fileName = binary <.> exeExtension

    search :: [FilePath] -> IO (Maybe FilePath)
    search [] = return Nothing
    search (d:ds) = do
        let path = d </> fileName
        b <- doesFileExist path
        if b then return (Just path)
             else search ds

findExecutable mustn't returns a file that it isn't an executable file, for example

(~/bin is in PATH variable)

$ touch ~/bin/foofile
$ ghci
$ :m System.Directory
$ findExecutable "foofile"

shows that findExecutable returns IO (Just "/home/iago/bin/foofile").

Altought is not a bug, could be good add a new funcion (findExecutables for example) to return all the executables in all the paths of PATH variable that matchs with a given filename (like which -a).

[igloo]

Thanks for the report; we should be able to fix this for 6.8.3.

For your proposed findExecutables addition, please follow the  library submissions procedure.

[igloo]

Hmm, the system function that we use on Windows returns the first path, regardless of whether or not it is executable. I think we should punt on this for now, and revisit it or 6.10.