Opened 3 years ago

Last modified 3 years ago

#12179 new bug

Incorrect parsing of a pattern synonym type

Reported by: mpickering Owned by:
Priority: normal Milestone:
Component: Compiler Version: 8.0.1
Keywords: PatternSynonyms Cc:
Operating System: Unknown/Multiple Architecture: Unknown/Multiple
Type of failure: None/Unknown Test Case:
Blocked By: Blocking:
Related Tickets: #12108 Differential Rev(s):
Wiki Page:


The following definition is accepted by GHC.

pattern Q :: a -> forall. (Bool -> a)
pattern Q v <- (($ True) -> v)

What does this type signature mean? Who knows. It should be rejected for being an invalid form.

Maybe see #12108

Change History (1)

comment:1 Changed 3 years ago by simonpj

See also #12187 which needs to be settled first.

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