[Yhc] Incomprehensible error messages
Malcolm.Wallace at cs.york.ac.uk
Wed Jun 6 12:17:09 EDT 2007
"David Fox" <ddssff at gmail.com> wrote:
> What I was wondering is what those "No default for Main.CNode"
> messages would be expected to mean. Maybe if I could supply the
> default it claims is missing I could work around this problem.
The message refers to the standard Haskell class-defaulting mechanism
(which is only supposed to cut in when there is an ambiguous constrained
type, and one of the constraints is Num). You can attempt to use the
user-defined defaulting feature of Haskell to workaround this
type-checker bug. e.g.
module Mine where
data TNode = ...
although I can't guarantee the results.
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