Add Show instance for ParserResult (fixes #95).

pcapriotti · Jul 30, 2014 · 19eed17 · 19eed17
1 parent 3b375db
commit 19eed17
Show file tree

Hide file tree

Showing 2 changed files with 13 additions and 0 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -4,6 +4,8 @@
 
 - Added low-level function to handle parse results (pull request \#94).
 
+- `ParserResult` now has a `Show` instance (see issue \#95).
+
 - Fixed bugs
     * \#93 - Formatting problem for several sub-parsers
 

diff --git a/Options/Applicative/Types.hs b/Options/Applicative/Types.hs
@@ -236,14 +236,25 @@ instance Monoid Completer where
 newtype CompletionResult = CompletionResult
   { execCompletion :: String -> IO String }
 
+instance Show CompletionResult where
+  showsPrec p _ = showParen (p > 10) $
+    showString "CompletionResult _"
+
 newtype ParserFailure = ParserFailure
   { execFailure :: String -> (String, ExitCode) }
 
+instance Show ParserFailure where
+  showsPrec p (ParserFailure f)
+    = showParen (p > 10)
+    $ showString "ParserFailure "
+    . showsPrec 11 (f "<program>")
+
 -- | Result of 'execParserPure'.
 data ParserResult a
   = Success a
   | Failure ParserFailure
   | CompletionInvoked CompletionResult
+  deriving Show
 
 type Args = [String]