Implement orphan instance for shell (#14)

hit-on.cabal

@@ -25,6 +25,7 @@ library
   exposed-modules:     Hit
                          Hit.Cli
                          Hit.ColorTerminal
+                         Hit.Shell
 
   autogen-modules:     Paths_hit_on
   other-modules:       Paths_hit_on
@@ -35,6 +36,7 @@ library
                      , gitrev ^>= 1.3
                      , optparse-applicative ^>= 0.14
                      , relude ^>= 0.4
+                     , process ^>= 1.6.3
 
   ghc-options:         -Wall
                        -Wincomplete-uni-patterns

src/Hit/Shell.hs

@@ -0,0 +1,23 @@
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE TypeFamilies      #-}
+
+{- | This module contains neat orphan instance for function to be able to call
+commands using just strings.
+-}
+
+module Hit.Shell
+       (
+       ) where
+
+import System.Process (callCommand, showCommandForUser)
+
+
+-- | This is needed to be able to call commands by writing strings.
+instance (a ~ Text, b ~ ()) => IsString ([a] -> IO b) where
+    fromString :: String -> [Text] -> IO ()
+    fromString cmd args = do
+        let cmdStr = showCommandForUser cmd (map toString args)
+        putStrLn $ "⚙  " ++ cmdStr
+        callCommand cmdStr