#12864: Produce type errors after looking at whole applications -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Currently, the type error messages we produce in case of function applications are rather dumb, in particular if arguments were ommited, added, swapped or not parenthized correctly. (Examples in the first comment below.) In many cases the error messages would be better if it would at one application if a function at once, and, in general, present the user with the (inferred) type of the function as well as the (expected) type due to the argument. This way, only one type error will be reported per function application, and comparing these two reported types will allow the user to spot the problem more easily. (With „one application“ I mean `e1 e2 e3 … en` where `e1` is not of that form.) Furthermore, once we have these two types in our hands, we can look for common patterns, and give even more helpful error messages, such as suggesting to swap two arguments. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12864 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler