#16373: Strings from symbolVal not simplified at compile time -------------------------------------+------------------------------------- Reporter: roland | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 (CodeGen) | 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: -------------------------------------+------------------------------------- Compiling {{{#!hs {-# LANGUAGE DataKinds, TypeApplications #-} module Test where import GHC.TypeLits import Data.Proxy testAA :: Bool testAA = symbolVal @"A" Proxy == symbolVal @"A" Proxy testAB :: Bool testAB = symbolVal @"A" Proxy == symbolVal @"B" Proxy testAB' :: Bool testAB' = symbolVal @"A" Proxy == symbolVal @"B" Proxy }}} with {{{ ghc -O -ddump-simpl -dsuppress-all Test.hs }}} yields: {{{ -- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0} testAB'2 testAB'2 = "B"# -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0} testAB'1 testAB'1 = unpackCString# testAB'2 -- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0} testAA2 testAA2 = "A"# -- RHS size: {terms: 2, types: 0, coercions: 0, joins: 0/0} testAA1 testAA1 = unpackCString# testAA2 -- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0} testAB' testAB' = eqString testAA1 testAB'1 -- RHS size: {terms: 1, types: 0, coercions: 0, joins: 0/0} testAB testAB = testAB' -- RHS size: {terms: 3, types: 0, coercions: 0, joins: 0/0} testAA testAA = eqString testAA1 testAA1 }}} Furthermore, removing the type signatures for ''either'' testAB or testAB' makes ''both'' simplify to False! I would expect all three definitions to simplify to True or False, independently of the presence of type signatures. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16373 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler