Shelly cannot see PATH… because on Windows it may be named Path

[mwu-tow]

Please consider the following program:

{-# LANGUAGE OverloadedStrings #-}

import qualified Shelly as Sh
import qualified System.Environment as Env

main :: IO ()
main = do
    print "PATH according to Shelly"
    (Sh.shelly $ Sh.get_env "PATH") >>= print
    print "PATH according to System.Environment"
    Env.getEnv "PATH" >>= print 

I'd expect that results of both Sh.get_env "PATH" and Env.getEnv "PATH" are the same (modulo Maybe), however to my surprise they are not.

H:\shelly>stack ghc Test.hs && test
Run from outside a project, using implicit global config
Using resolver: lts-3.5 from global config file: C:\s\global\stack.yaml
Continuing despite missing tool: msys2
[1 of 1] Compiling Main             ( Test.hs, Test.o )
Linking Test.exe ...
"PATH according to Shelly"
Nothing
"PATH according to System.Environment"
"C:\\CUDA\\Toolkit\\bin;C:\\CUDA\\Toolkit\\libnvvp;C:\\thingsInPath;C:\\Python27\\;C:\\Python27\\Scripts;C:\\Perl64\\site\\bin;C:\\Perl64\\bin;C:\\ProgramData\\Oracle\\Java\\javapath;C:\\Users\\mwurb_000\\AppData\\Roaming\\cabal\\bin;C:\\Program Files (x86)\\Intel\\iCLS Client\\;C:\\Program Files\\Intel\\iCLS Client\\;C:\\Program Files (x86)\\Git\\bin;C:\\WINDOWS\\system32;C:\\WINDOWS;C:\\WINDOWS\\System32\\Wbem;C:\\WINDOWS\\System32\\WindowsPowerShell\\v1.0\\;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\DAL;C:\\Program Files\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files (x86)\\Intel\\Intel(R) Management Engine Components\\IPT;C:\\Program Files (x86)\\Windows Kits\\8.1\\Windows Performance Toolkit\\;C:\\Program Files\\Microsoft SQL Server\\110\\Tools\\Binn\\;C:\\Program Files (x86)\\Microsoft SDKs\\TypeScript\\1.0\\;C:\\Program Files (x86)\\CMake\\bin;C:\\Program Files (x86)\\QuickTime\\QTSystem\\;C:\\Program Files\\Microsoft SQL Server\\120\\Tools\\Binn\\;C:\\Program Files (x86)\\Subversion\\bin;C:\\Program Files (x86)\\Skype\\Phone\\;C:\\Program Files\\Microsoft DNX\\Dnvm\\;C:\\Program Files (x86)\\NVIDIA Corporation\\PhysX\\Common;C:\\Program Files\\TortoiseGit\\bin;C:\\Program Files\\OpenVPN\\bin;C:\\Users\\mwurb_000\\AppData\\Local\\Programs\\minghc-7.8.4-x86_64\\switch;C:\\Ruby21-x64\\bin;C:\\Users\\mwurb_000\\AppData\\Local\\atom\\bin;C:\\ProgramData\\chocolatey\\bin;"

After some more experiments I think I got why Shelly cannot get PATH. On my Windows machine this environment variable is named Path. Apparently Shelly's get_env is case-sensitive. It should not be.
Because of that not only getting the environment fails but it also breaks functions like which.

[gregwebs]

Thanks for reporting. Looks like for Window shelly needs to use the case-insensitive package (or perhaps toLower)