#14265: kinded holes -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.1 checker) | Keywords: Resolution: | PartialTypeSignatures 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 RyanGlScott): * keywords: => PartialTypeSignatures * component: Compiler => Compiler (Type checker) Comment: You didn't give a concrete example of what you'd like to see, so I'm forced to guess. My shot-in-the-dark attempt is this program: {{{#!hs {-# LANGUAGE PolyKinds #-} f :: proxy _ -> () f _ = () }}} {{{ GHCi, version 8.2.1: http://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /home/rgscott/.ghci [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:3:12: error: • Found type wildcard ‘_’ standing for ‘w’ Where: ‘w’ is a rigid type variable bound by the inferred type of f :: proxy w -> () at Bug.hs:4:1-8 ‘k’ is a rigid type variable bound by the inferred type of f :: proxy w -> () at Bug.hs:4:1-8 To use the inferred type, enable PartialTypeSignatures • In the type signature: f :: proxy _ -> () | 3 | f :: proxy _ -> () | ^ }}} This output is indeed pretty skeevy-looking¸ since it points out a kind variable `k` in a `Where:` clause, but `k` isn't used anywhere else! Perhaps you wanted to see something like this instead? {{{ • Found type wildcard ‘_’ standing for ‘w’ (of kind ‘k’) Where: ... }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14265#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14265: kinded holes -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 8.2.1 checker) | Keywords: Resolution: | PartialTypeSignatures 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 Simon Peyton Jones ): In [changeset:"1b476ab55be6c2c553988cc63d8e0c5473136275/ghc" 1b476ab5/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="1b476ab55be6c2c553988cc63d8e0c5473136275" Improve type-error reporting This patch does two things: * When reporting a hole, we now include its kind if the kind is not just '*'. This addresses Trac #14265 * When reporting things like "'a' is a rigid type varaible bound by ...", this patch arranges to group the type variables together, so we don't repeat the "bound by..." stuff endlessly }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14265#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#14265: kinded holes -------------------------------------+------------------------------------- Reporter: lspitzner | Owner: (none) Type: feature request | Status: closed Priority: normal | Milestone: 8.4.1 Component: Compiler (Type | Version: 8.2.1 checker) | Keywords: Resolution: fixed | PartialTypeSignatures 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 lspitzner): thanks! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14265#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler