[Haskell-cafe] Alternate instance Show (Maybe a)?

ajb at spamcop.net ajb at spamcop.net
Sun Feb 4 05:34:03 EST 2007

G'day all.

Quoting Sergey Zaharchenko <doublef-ctm at yandex.ru>:

> Yes, I think another Show-like class will probably be a better
> solution...

This is the one that I use.  Very simple.

    import Text.PrettyPrint.HughesPJ

    class Pretty a where
        -- Equivalent of showsPrec
        prettyP :: Int -> a -> Doc
        prettyP _ x = pretty x

        -- Equivalent of shows
        pretty :: a -> Doc
        pretty x = prettyP 0 x

Andrew Bromage

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