The definition of <icdecl> in the interface syntax is:
<icdecl> ::= <vars> :: <type>
ie no context is allowed in the type signature. The corresponding
definition in an implementation is:
<csign> ::= <vars> :: [<context =>] <type>
This is used in PreludeCore at the top of page 92, where we have:
class (Real a, Fractional a) => RealFrac a where
properFraction :: (Integral b) => a -> (b,a)
...
According to the definition of <icdecl>, the interface for PreludeCore would be:
class (Real a, Fractional a) => RealFrac a where
properFraction :: a -> (b,a)
...
which is clearly quite different. Shouldn't <icdecl> allow a context?
-Norman
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Messing about with signature files fills a much-needed gap in the working
day.
