#10134: Pattern Matching Causes Infinite Type Error -------------------------------------+------------------------------------- Reporter: dongen | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.4 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Howsagoin, This is a report about ghci (7.8.4) with CLaSH 0.4.1 I have a collection of modules that show an odd error. I don't want to send them to the list but I can send them to the developers if they think the described behaviour is definitely an error, which I suspect it is. When I write:
(a,b) = expression
I get a type error about an occurs check: cannot construct infinite type: t0 ~ (t0 + 1) -1. The error message doesn't mention t0. However, when I leave out the pattern matching on the tuple and write
var = expression a = fst var b = snd var
where var is a fresh variable, everything is fine. This is odd, because all I did was stripping off the pattern matching. To make sure, I also tried
var = expression (a,b) = var
This also gave the same type checking error. If there's anybody willing to have a look at this, please feel free to contact me by email. If you think I should produce a small example, also please let me know, but please note that it already took me several hours before I found that leaving out the pattern matching solved the problem:-( TIA for your time. Marc van Dongen dongen@cs.ucc.ie -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10134 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler