Question

Is it way to check whether given string represent executable in $PATH(%path%)?
It have to be portable to Windows. Idea to just call it and see return status is not apporiate,
as non-zero may mean program error or program not found.
Well, in code, I want following

possibleCompilers = ["gcc", "icc", "foo", "bar.exe"]
presentCompiler :: IO String

Answer 1

That task should be doable using System.Directory.findExecutable.

possibleCompiler :: IO (Maybe String)
possibleCompiler = check possibleCompilers
  where
    check [] = return Nothing
    check (c:cs) = do
       mbc <- findExecutable c
       case mbc of
         Just _ -> return mbc
         Nothing -> check cs

I changed the type to IO (Maybe String), since maybe, none of the candidates is found.