Folks, Another small but long-standing bug in the Haskell Library report: the recursive calls to 'reads' and 'shows' in the Read and Show instances for Ratio and Array should be calls to readsPrec and showsPrec respectively. The corrected defintions are below. (c.f. the example of derived instances in Appendix D of the language report.) Anyone disagree? (How do these bugs last so long?) Simon ================== Page 5 ======================== instance (Read a, Integral a) => Read (Ratio a) where readsPrec p = readParen (p > prec) (\r -> [(x%y,u) | (x,s) <- readsPrec (prec+1) r, ("%",t) <- lex s, (y,u) <- readsPrec (prec+1) t ]) instance (Integral a) => Show (Ratio a) where showsPrec p (x:%y) = showParen (p > prec) (showsPrec (prec+1) x . showString " % " . showsPrec (prec+1) y) ================== Page 24 ======================== instance (Ix a, Show a, Show b) => Show (Array a b) where showsPrec p a = showParen (p > arrPrec) ( showString "array " . showsPrec (arrPrec+1) (bounds a) . showChar ' ' . showsPrec (arrPrec+1) (assocs a) ) instance (Ix a, Read a, Read b) => Read (Array a b) where readsPrec p = readParen (p > arrPrec) (\r -> [ (array b as, u) | ("array",s) <- lex r, (b,t) <- readsPrec (arrPrec+1) s, (as,u) <- readsPrec (arrPrec+1) t ]) -- Precedence of the 'array' function is that of application itself arrPrec = 10