#8474: Extremely slow compilation of a program with multiply implicit parameters --------------------------------------------+------------------------------ Reporter: akamaus | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Old description:

Adding yet another ?tstX variable in this snippet slows down compilation by a factor of ten or so. Giving an explicit type annotation to tst1 makes compilation instant.

{-# LANGUAGE ImplicitParams #-}

data D = D Int deriving Show

slow_to_compile :: IO () slow_to_compile = do tst1 <- return 1

let ?tst1 = tst1 let ?tst2 = tst1 let ?tst3 = tst1 let ?tst4 = tst1 let ?tst5 = tst1 let ?tst6 = tst1 let ?tst7 = tst1

print $ D ?tst1

New description: Adding yet another ?tstX variable in this snippet slows down compilation by a factor of ten or so. Giving an explicit type annotation to tst1 makes compilation instant. {{{ {-# LANGUAGE ImplicitParams #-} data D = D Int deriving Show slow_to_compile :: IO () slow_to_compile = do tst1 <- return 1 let ?tst1 = tst1 let ?tst2 = tst1 let ?tst3 = tst1 let ?tst4 = tst1 let ?tst5 = tst1 let ?tst6 = tst1 let ?tst7 = tst1 print $ D ?tst1 }}} -- Comment (by simonpj): Yes, you're right. We'll fix this! Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8474#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#8474: Extremely slow compilation of a program with multiply implicit parameters --------------------------------------------+------------------------------ Reporter: akamaus | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type checker) | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: --------------------------------------------+------------------------------ Comment (by Simon Peyton Jones ): In [changeset:"04f6ddd0e56fd21a399d17634533dfaf89b25773/testsuite"]: {{{ #!CommitTicketReference repository="testsuite" revision="04f6ddd0e56fd21a399d17634533dfaf89b25773" Test Trac #8474 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8474#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler