#16339: Cannot put (.) or (!) into an export list -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.7 (Parser) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Thanks to recent work in GHC HEAD, it is now possible to define type operators named `(.)` and `(!)`: {{{#!hs type (f . g) x = f (g x) type x ! f = f x }}} However, I was surprised to discover that it's not possible to put them in an export list! That is to say, this program doesn't parse: {{{ {-# LANGUAGE TypeOperators #-} module Bug (type (.), type (!)) where type (f . g) x = f (g x) type x ! f = f x }}} {{{ $ ~/Software/ghc4/inplace/bin/ghc-stage2 --interactive Bug.hs GHCi, version 8.7.20190219: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci Bug.hs:2:19: error: parse error on input ‘.’ | 2 | module Bug (type (.), type (!)) where | ^ }}} This problem appears to be specific to the `(.)` and `(!)` type operators, since any other type operator will work in its place: {{{#!hs {-# LANGUAGE TypeOperators #-} module Works (type (&)) where type (f & g) x = f (g x) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16339 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler