Presented by Neil Sculthorpe.

In Haskell, there are many data types that would form monads were it not for the presence of type-class constraints on the operations on that data type. This is a frustrating problem in practice, because there is a considerable amount of support and infrastructure for monads that these data types cannot use. This talk will demonstrate that a monadic computation can be restructured into a normal form such that the standard monad class can be used. The technique is not specific to monads --- it can also be applied to other structures, such as applicative functors. One significant use case for this technique is Domain Specific Languages, where it is often desirable to compile a deep embedding of a computation to some other language, which requires restricting the types that can appear in that computation.

See the mailing list for details on this month's agenda: https://groups.google.com/forum/#!forum/pdxfunc

ABOUT THE GROUP: Join programmers, researchers and enthusiasts to discuss functional programming. pdxfunc is a study/user group exploring the world of functional programming based in Portland, Oregon. The group welcomes programmers interested in all functional languages, including Haskell, OCaml, Erlang, Scala and others, as well as using functional techniques in non-functional languages. The group meets regularly and provides presentations, demos and discussions applicable to all skill levels, from newbies and experts. The meetings are usually on the second Monday of the month.