Hello Olivier, On Mon, Jul 09, 2018 at 01:31:07PM +0200, Olivier Revollat wrote:
In the second case, it's a simple recursion, so far so good ... but when I look at the implementation of "forever" i can't wrap my head around :
http://hackage.haskell.org/package/base-4.11.1.0/docs/src/Control.Monad.html...
forever a = let a' = a *> a' in a' `*>` is the same as `>>` (if you have ever met `>>`), with the difference that the latter works on monads only. In do notation, we could write forever :: Monad m => m a -> m b forever a = let a' = do a a' in do a' Which should be easier to get: we `do` a'; a' is nothing but a and a', so we do a and then a', which is nothing but a and a', etc. Does this explanation feel right? As soon as you can, familiarise yourself what the do notation desugars to: in my opinion plain operators are clearer -F