#2696: forall not recognized in RULES
---------------------------------+------------------------------------------
Reporter: conal | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.11 | Severity: normal
Keywords: | Testcase:
Architecture: Unknown/Multiple | Os: Unknown/Multiple
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{{{
{-# LANGUAGE GADTs, TypeFamilies, TypeOperators
-- , ScopedTypeVariables
#-}
{-# OPTIONS_GHC -Wall -frewrite-rules #-}
-- ScopedTypeVariables works around a 6.10 bug. The forall keyword is
-- supposed to be recognized in a RULES pragma, but it's not.
--
-- This bug was introduced between ghc 6.9.20080622 and 6.10.0.20081007.
-- | Mapping from all elements of @a@ to the results of some function
class HasTrie a where
-- | Representation of trie with domain type @a@
data (:->:) a :: * -> *
-- Create the trie for the entire domain of a function
trie :: (a -> b) -> (a :->: b)
-- | Convert a trie to a function, i.e., access a field of the trie
untrie :: (a :->: b) -> (a -> b)
{-# RULES
"trie/untrie" forall t. trie (untrie t) = t
"untrie/trie" forall f. untrie (trie f) = f
#-}
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2696>
GHC <http://www.haskell.org/ghc/>
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