#15944: Wrong warning given ViewPatterns and -Wmonomorphism-restriction -------------------------------------+------------------------------------- Reporter: pacak | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.3 Component: Compiler | Version: 8.6.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I understand ghc complaining about `b`, but not about `a`. No warnings when view patterns are not used. {{{#!hs {-# LANGUAGE ViewPatterns #-} {-# OPTIONS -Wmonomorphism-restriction #-} module Foo where {- demo.hs:11:9: warning: [-Wmonomorphism-restriction] • The Monomorphism Restriction applies to the bindings for ‘a’, ‘b’ Consider giving them a type signature • In the expression: let Foo a (round -> b) = f in a + b In an equation for ‘bar’: bar f = let Foo a (round -> b) = f in a + b | 11 | let Foo a (round -> b) = f | ^^^^^^^^^^^^^^^^^^^^^^ -} data Foo = Foo Int Double bar :: Foo -> Int bar f = let Foo a (round -> b) = f in a + b }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15944 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler