At 21:40 22/11/04 +0100, Ralf Laemmel wrote:
Instance selection and thereby overlapping resolution is *independent* of constraints. It is defined to be purely syntactical in terms of instance heads. See the HList paper for some weird examples.
That explains it. Thanks! #g --
Ralf
Graham Klyne wrote:
The reported overlapping instance is [Char], which I take to be derived from the type constructor [] applied to type Char, this yielding a form that matches (cw c). But the instance ConceptExpr (cw c) is declared to be dependent on the context ConceptWrapper cw c, which has *not* been declared for the type constructor [].
GHCi with -fglasgow-exts is no more informative.
What am I missing here?
------------ Graham Klyne For email: http://www.ninebynine.org/#Contact