#9889: Pattern synonym does not work in top-level pattern bind -------------------------------------+------------------------------------- Reporter: goldfire | Owner: cactus Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.9 (Type checker) | Keywords: PatternSynonyms Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Unknown Unknown/Multiple | Blocked By: Type of failure: GHC | Related Tickets: rejects valid program | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by cactus): * failure: None/Unknown => GHC rejects valid program * component: Compiler => Compiler (Type checker) Old description:
When I say
{{{ pattern Id x = x
Id x = True }}}
I get
{{{ Not in scope: data constructor ‘Id’ }}}
This happens with both 7.8.3 and HEAD.
New description: When I say {{{ {-# LANGUAGE PatternSynonyms #-} pattern Id x = x Id x = True }}} I get {{{ Not in scope: data constructor ‘Id’ }}} This happens with both 7.8.3 and HEAD. -- Comment: Note that pattern binds, in general, don't have this problem, only at the top level; e.g. the following works as expected: {{{ {-# LANGUAGE PatternSynonyms #-} pattern Id x = x foo = x where Id x = True }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9889#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler