{- |

Module : $Header$

Copyright : (c) jianchun wang and Uni Bremen 2006

License : similar to LGPL, see HetCATS/LICENSE.txt or LIZENZ.txt

Maintainer : wjch868@tzi.de

Stability : provisional

Portability : portable

some instances for the class Pretty

-}

module Common.DocUtils where

import Common.Doc

instance (Pretty a, Pretty b) => Pretty (Either a b) where

pretty = printEither pretty pretty

printEither :: (a->Doc) -> (b->Doc) -> Either a b -> Doc

printEither fA fB ei = case ei of

Left x -> fA x

Right x -> fB x

instance Pretty a => Pretty (Maybe a) where

pretty = printMaybe pretty

printMaybe :: (a->Doc) -> Maybe a -> Doc

printMaybe fA mb = case mb of

Just x -> fA x

Nothing -> empty

instance (Pretty a, Pretty b) => Pretty (a, b) where

pretty = printPaar pretty pretty

printPaar :: (a->Doc) -> (b->Doc) -> (a,b) -> Doc

printPaar fA fB (a,b) =

lparen <> fA a <> comma <> fB b <> rparen

instance (Pretty a, Pretty b, Pretty c) => Pretty (a, b, c) where

pretty = printTriples pretty pretty pretty

printTriples :: (a -> Doc) -> (b -> Doc) -> (c -> Doc) -> (a, b, c) -> Doc

printTriples fA fB fC (a,b,c) =

lparen <> fA a <> comma <> fB b <> comma <> fC c <> rparen

instance Pretty Int where

pretty = text . show