#8233: Type environment when reporting holes -------------------------------------+------------------------------------- Reporter: monoidal | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler (Type | Version: 7.7 checker) | Operating System: Unknown/Multiple Keywords: | Type of failure: Incorrect Architecture: Unknown/Multiple | warning at compile-time Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #8191 | -------------------------------------+------------------------------------- This is a sequel to #8191. Consider {{{ {-# LANGUAGE TypeHoles #-} u1 = 0 u2 = 0 u3 = 0 u4 = 0 u5 = 0 u6 = 0 f :: a -> (a -> b) -> b f x y = _b v1 = 0 v2 = 0 v3 = 0 v4 = 0 v5 = 0 v6 = 0 }}} Compile with `-fno-max-relevant-binds` and see {{{ Relevant bindings include v6 :: a0 (bound at THoles.hs:18:1) v5 :: a1 (bound at THoles.hs:17:1) v4 :: a2 (bound at THoles.hs:16:1) v3 :: a3 (bound at THoles.hs:15:1) v2 :: a4 (bound at THoles.hs:14:1) v1 :: a5 (bound at THoles.hs:13:1) f :: a -> (a -> b) -> b (bound at THoles.hs:11:1) x :: a (bound at THoles.hs:11:3) y :: a -> b (bound at THoles.hs:11:5) }}} The list is inverted: `v6` is first, while it was last. If we do not use `-fno-max-relevant-binds` then local parameters `x` and `y` are not visible at all, but they are the most important data. Another aspect is that we see `v1, v2` but not `u1, u2`. I'm not sure what is a good solution here. Display everything? Only N bindings above `f` and N bindings below `f`? People usually write code top to bottom, so preceding bindings should be more useful in general than following ones. I think this case deserves some attention because it will often occur in practice (putting a hole in any large file). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8233 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler