| ... | ... | @@ -22,8 +22,8 @@ the memory-model semantics of IORefs. |
|
|
|
|
|
|
|
|
|
|
|
The work on the class system has focused on resolving the [MultiParamTypeClassesDilemma](multi-param-type-classes-dilemma). The core of the dilemma is that multi-parameter typeclasses are a popular extension
|
|
|
|
that are strongly desired in Haskell'. However, many important uses of MPTCs (like the monad transformer library) require additional extensions to resolve ambiguities in their typechecking. Historically, FunctionalDependecies? have been used for this purpose, but they are very tricky to implement and are also difficult to specify in a way that
|
|
|
|
guarantees the termination of typechecking. [AssociatedTypes](associated-types) are a possible replacement, but they have not yet been completely implemented in any Haskell implementation.
|
|
|
|
that is strongly desired for Haskell'. However, many important uses of MPTCs (like the monad transformer library) require additional extensions to resolve ambiguities in their typechecking. Historically, [FunctionalDependencies](functional-dependencies) have been used for this purpose, but they are very tricky to implement and are also difficult to specify in a way that
|
|
|
|
guarantees the termination of typechecking. [AssociatedTypes](associated-types) are a possible replacement, but our current implementation experience with them is very limited. The subcommittee has explored several ways to resolve this dilemma (including restricted FDs, fast-tracked ATs and FDs as a "blessed" extension), but, so far, no consensus has emerged. Our current plan is to focus on writing other parts of the Haskell' standard, in the hopes that additional implementation experience with ATs will clarify the situation.
|
|
|
|
|
|
|
|
## Libraries
|
|
|
|
|
| ... | ... | |