From: Samir Benmendil <me@rmz.io>
Date: Sat, 20 Jan 2018 22:12:51 +0000 (+0000)
Subject: `deriving` from `Show` is a really easy way to print values
X-Git-Url: https://git.rmz.io/my-scheme.git/commitdiff_plain/5988ad89d4dd34b63abf5512ce3308ed86ff279d?ds=inline

`deriving` from `Show` is a really easy way to print values

Probably only works for type that can already be shown.
---

diff --git a/app/Main.hs b/app/Main.hs
index 67ec8dd..01fd038 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -9,6 +9,7 @@ data LispVal = Atom String
              | Number Integer
              | String String
              | Bool Bool
+             deriving Show
 
 symbol :: Parser Char
 symbol = oneOf "!#$%&|*+-/:<=>?@^_~"
@@ -46,7 +47,7 @@ parseExpr = parseString
 readExpr :: String -> String
 readExpr input = case parse parseExpr "lisp" input of
     Left err -> "No match: " ++ show err
-    Right val -> "Found value"
+    Right val -> "Found value: " ++ show val
 
 main :: IO ()
 main = do