[Haskell-cafe] Practical introduction to monads

Greg Buchholz haskell at sleepingsquirrel.org
Tue Aug 2 17:21:00 EDT 2005

Paul Moore wrote:
> One thing I haven't found a really good discussion of, is practical
> examples of building monads. There's plenty of discussion of the IO
> monad, and the state monad, and a lot of good theory on monads, but
> although I've seen tantalising statements about how powerful the
> ability to define your own monads can be, but no really concrete
> examples - something along the lines of
>   - here is problem X
>   - this might be our first cut at coding it
>   - we can abstract out this stuff, as a monad
>   - see how the code looks now, how much cleaner it is

    Maybe you could try going in the opposite direction, and convert
something like monadic parser combinators...


...it into their non-monadic form (explictly passing the parsed string

> I've only skimmed - so pointers to areas in these documents I might
> have missed would be appreciated. On the other hand, pointers to
> papers I've missed altogether would also be gratefully received.

    I found the papers by Philip Wadler to be the most helpful...


...especially _Monads for functional programming_ and 
_Imperative functional programming_.

Greg Buchholz

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