#12020: Error message on use of != should suggest use of /= -------------------------------------+------------------------------------- Reporter: mhoermann | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: 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 Iceland_jack): Replying to [comment:1 nomeata]: I like it, comments: Do you have more motivational examples, I have a feeling this would mostly be used for operators. Would it appear in `:info (/=)` output? What about `:info (!=)` whether or not it's defined. Would it be attached to the definition or definable in a separate module? Adding a custom error message. I take it that the first definition was supposed to be `(/=) :: a -> a -> Bool`: {{{#!hs class Eq a where (==) :: a -> a -> Bool (/=) :: a -> a -> Bool {-# MISSPELLINGS (/=) AS (!=) "‘Not equal to’ is (/=), syntactically emulating the the math symbol ≠" #-} class Eq a => Bits a where (.&.) :: a -> a -> a {-# MISSPELLINGS (.&.) AS (&) "Bitwise and is (.&.)." #-} (.|.) :: a -> a -> a {-# MISSPELLINGS (.|.) AS (|) "Bitwise or is (.|.)." #-} ... shiftL :: a -> Int -> a {-# MISSPELLINGS shiftL AS (<<) "Left shift" #-} }}} `(|)` doesn't parse but oh well {{{ ghci> 4 != 10 _--_ It looks like you're trying Ö Ö ,- to code. ‘Not equal to’ is (/=), syntactically || | ' emulating the the math symbol ≠. Try writing |\_|/ ‘4 /= 10’ instead. \_/ }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12020#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler