Malformed class assertion with GHCi's output (a -> a ~ T a)

[Simon Peyton-Jones]

Thanks.   I've fixed this.

Ian: pls merge if time.

Simon

Fri Oct  2 12:15:49 BST 2009  simonpj at microsoft.com
  * Fix pretty-printing precedence for equality constraints

    M ./compiler/types/TypeRep.lhs -1 +7


From: glasgow-haskell-users-bounces at haskell.org [mailto:glasgow-haskell-users-bounces at haskell.org] On Behalf Of Sean Leather
Sent: 15 September 2009 12:51
To: GHC Users List
Subject: Malformed class assertion with GHCi's output (a -> a ~ T a)

I queried (:t) the type of something in GHCi, and it told me the value should have the constraint (a -> a ~ T a) among others. When I tried to use this in code, I got a "malformed class assertion." So, I put parentheses around the function type, ((a -> a) ~ T a), and everybody is happy again. Is there something off about the precedence of (~) vs. (->)? Should GHCi print the parentheses?

I'm using GHC 6.10.1, so this might already be fixed.

Regards,
Sean
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