Hi Andrew, Andrew Coppin wrote:
Uh... what's Applicative? (I had a look at Control.Applicative, but it just tells me that it's "a strong lax monoidal functor". Which isn't very helpful, obviously.)
Seriously, what are you talking about? The haddock page for Control.Applicative hoogle links to begins with
This module describes a structure intermediate between a functor and a monad: it provides pure expressions and sequencing, but no binding. (Technically, a strong lax monoidal functor.) For more details, see Applicative Programming with Effects, by Conor McBride and Ross Paterson, online at http://www.soi.city.ac.uk/~ross/papers/Applicative.html.
This interface was introduced for parsers by Niklas Röjemo, because it admits more sharing than the monadic interface. The names here are mostly based on recent parsing work by Doaitse Swierstra.
This class is also useful with instances of the Traversable class.
I agree that this is hard to understand, but it's more then just "strong lax monoidal functor", isn't it? More importantly, there is a reference to a wonderful and easy to read paper. (easy in the "easy for Haskell programmers" sense, not in the "easy for the authors, and maybe the inventors of Haskell" sense). Just give it a try. Just in case you missed the link for some reason, here is it again: http://www.soi.city.ac.uk/~ross/papers/Applicative.html Tillmann PS. Regarding Applicative, you may be interested in the original proposal introducing it, which can be found here: http://www.soi.city.ac.uk/~ross/papers/Applicative.html PPS. Don't miss McBride's and Peterson's great paper about applicative functors at http://www.soi.city.ac.uk/~ross/papers/Applicative.html. PPPS. You may also be interested in http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf. PPPPS. If you wonder what do to next when visiting http://www.soi.city.ac.uk/~ross/papers/Applicative.html, you could consider clicking on the link to http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf. Its a very interesting paper, well, actually, it reads more like a tutorial. Just like a blog post, but so much better then the usual blog post.