Ticket #301 (closed bug: fixed)
GADT constructor constraints ignored
|Reported by:||wolfram_kahl||Owned by:||simonpj|
|Component:||Compiler (Type checker)||Version:||6.4|
|Type of failure:||Difficulty:||Unknown|
|Test Case:||gadt/karl1, gadt/karl2||Blocked By:|
Description (last modified by simonmar) (diff)
Class constraints on GADT constructore appear to be ignored. I tried: data Expr :: * -> * where Const :: Show a => a -> Expr a Apply :: Fct a b -> Expr a -> Expr b and there is no way to define the expected constraint-less Show instance --- for details, see Expr0.lhs.
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