#10284: Create a dedicated `TypeError` exception type -------------------------------------+------------------------------------- Reporter: kosmikus | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Ticket #10283 discusses using `-fdefer-type-errors` to test that certain programs do not type check. In practice, this involves evaluating certain expressions to WHNF at run- time can checking whether they trigger an exception. Currently, it seems the exception to catch is an `ErrorCall` exception. It would be nice if we could very specifically catch type errors though. It's entirely possible that a critical test case that I want to be a type error mistakenly type- checks and then calls `error`. In such a situation, it's hard to distinguish such a true run-time error from a deferred type error. It would be much nicer if something like `TypeError` would be thrown instead of `ErrorCall`. Yes, it's currently possible to look at the text of the `ErrorCall` and check for certain text fragments in there, but that sounds extremely fragile to me. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10284 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler