[GHC] #12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)`
#12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)` -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ GHCi, version 8.1.20160920: http://www.haskell.org/ghc/ :? for help Prelude> let (#) = (+) Prelude> :set -XUnboxedSums Prelude> let (#) = (+) <interactive>:3:7: error: parse error on input ‘)’ }}} I first noticed this in an import statement: {{{ import Data.Functor.Utils (Max(..), Min(..), (#.)) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12605 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)` -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by rwbarton): Well, `UnboxedTuples` does the same. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12605#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)` -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by jberryman): Oh I see you're right, and maybe this is a dup of https://ghc.haskell.org/trac/ghc/ticket/12459 However even if that's expected under `UnboxedTuples`, this seems to be a worse situation under `UnboxedSums`. I'm looking at https://ghc.haskell.org/trac/ghc/wiki/UnpackedSumTypes under "Unpacking ... This part is not yet implemented..." it seems to me the intention is to allow `UnboxedSums` to automatically optimize (has this been implemented in HEAD yet btw?): {{{ data T1 a = Some a | None data T2 a = C {-# UNPACK #-} !(T1 a) }}} So a user might like to enable on a source tree for purposes of optimization; they don't need or want access to any new syntax. Let me know if I should open any new tickets. Feel free to do whatever you think with this one. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12605#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)` -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by jberryman): * cc: osa1 (added) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12605#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#12605: UnboxedSums causes parse error on hash operator e.g. `let (#) = (+)` -------------------------------------+------------------------------------- Reporter: jberryman | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: invalid | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by rwbarton): * status: new => closed * resolution: => invalid Comment: Presumably you won't need to enable any language extensions in order to take advantage of optimizations that use unboxed sums. There are already important optimizations that introduce unboxed tuples, and they don't require a language extension. These language extensions just allow you to write unboxed sums/tuples in the surface syntax. I guess I'll close this ticket since I don't think we should do anything here, though I don't feel too strongly about it. By the way, the workaround for the original issue is to add a space before `#.`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12605#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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