On 3 January 2012 08:46, <googlegro...@khinsen.fastmail.net> wrote: > Dragan R writes: > > > On the net I read that "Impure functional programming doesn't really > > need monads." > > and "It appears that in the presence of mutable state, a lot of the > > advantages of monads become moot." > > Monads are an abstraction mechanism, so you never need them. You can > always use the lower-level techniques in terms of which monads are > implemented.
This +1. You need to be more specific about what you mean when you say code "uses monads". In one sense, any code which uses a 'for' sequence comprehension is using a monad, because it satisfies all of the properties of a monad. In another sense, only code which contains and names specific things as monads, and uses general operators which apply to all monads, is using them. I've been using monads a lot recently with Overtone -- by which I mean I've been using (state-t cont-m), the continuation monad transformed to add state. I'm using it because: a) I want to simulate state representing the current beat number, and b) I want to schedule future events using apply-at; so rather than returning from a function to continue a melody, I call apply-at and pass the current continuation to it. As an example of what I've achieved, see this gist: https://gist.github.com/1441831 Using clojure.algo.monads, I have created a basic DSL which allows me to say (wait 1) to pause for one beat, and (at-current-beat (foo)) to schedule event (foo) to happen on the current beat. These commands are relative to the current time, but using monads I can transform them into commands at an absolute time using overtone's built-in 'at and 'apply-at macros, and to automagically handle the scheduling. This is a work in progress; I'm planning a fuller write-up of what I'm doing which I will send to the overtone list once I've ironed out the wrinkles. Phil -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
