generics - Haskell construct a type contains class -


i want construct haskell type:

    type singlepp = (string,glattice)

where glattice defined as:

    class glattice l         join :: l->l->l         ....

is there way me that?

type singlepp = (string, a)

and when use singlepp in function, restrict a glattice

somefunc :: glattice => singlepp -> () somefunc = domagic

if like, can use more type system-foo , go existential types, let avoid boilerplate after each function, in exchange must use language extension , data declaration explicit constructor. means more pattern matching when want @ a less typing in type declarations.

however of types can inferred.


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