[GHC] #8625: GHCi does not support some TH elements, while those elemenst are working in hs files
#8625: GHCi does not support some TH elements, while those elemenst are working in hs files ------------------------------------+------------------------------------- Reporter: danilo2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.7 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Hello. Below is a code, which works when using runhaskell, but does not work in GHCi. In GHCi we get following error: runQ [d| instance ( y ~ (t->t) ) => Member Vector y where member v = test |] <interactive>:19:6: Exotic predicate type not (yet) handled by Template Haskell y ~ (t -> t) code: {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE FlexibleContexts #-} {-# LANGUAGE UndecidableInstances #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE TemplateHaskell #-} module Main where import Language.Haskell.TH class a ~ b => HEq a b test :: a -> a test x = x data Vector class Member a b where member :: a -> b main :: IO () main = print =<< runQ [d| instance y ~ (t->t) => Member Vector y where member v = test |] -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8625 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8625: GHCi does not support some TH elements, while those elemenst are working in hs files -------------------------------------+------------------------------------ Reporter: danilo2 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.7 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by danilo2): We discovered now, that the error not always appears in GHCi session. It appears if we use following commands: :set -XTypeFamilies :set -XTemplateHaskell :set -XUndecidableInstances :set -XFlexibleInstances :set -XMultiParamTypeClasses :m + Language.Haskell.TH data Vector = Vector let test x = x class Member a f where member :: a -> f runQ [d| instance ( y ~ (t->t) ) => Member Vector y where member v = test |] <interactive>:19:6: Exotic predicate type not (yet) handled by Template Haskell y ~ (t -> t) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8625#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
#8625: GHCi does not support some TH elements, while those elemenst are working in
hs files
-------------------------------------+------------------------------------
Reporter: danilo2 | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: GHCi | Version: 7.7
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture: Unknown/Multiple
Type of failure: None/Unknown | Difficulty: Unknown
Test Case: | Blocked By:
Blocking: | Related Tickets:
-------------------------------------+------------------------------------
Comment (by Simon Peyton Jones
#8625: GHCi does not support some TH elements, while those elemenst are working in
hs files
-------------------------------------+------------------------------------
Reporter: danilo2 | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: GHCi | Version: 7.7
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture: Unknown/Multiple
Type of failure: None/Unknown | Difficulty: Unknown
Test Case: | Blocked By:
Blocking: | Related Tickets:
-------------------------------------+------------------------------------
Comment (by Simon Peyton Jones
#8625: GHCi does not support some TH elements, while those elemenst are working in hs files -------------------------------------+------------------------------------ Reporter: danilo2 | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: GHCi | Version: 7.7 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: th/T8625 | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Changes (by simonpj): * status: new => closed * testcase: => th/T8625 * resolution: => fixed Comment: Thank you. This one was easy, happily. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8625#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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