From: Jim Pryor Date: Wed, 1 Dec 2010 06:46:22 +0000 (-0500) Subject: lists-monad tweaks X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=8105e467b373e9da58fa80c748c97b1d485986c3;ds=sidebyside lists-monad tweaks Signed-off-by: Jim Pryor --- diff --git a/list_monad_as_continuation_monad.mdwn b/list_monad_as_continuation_monad.mdwn index a97e7e36..81a5be31 100644 --- a/list_monad_as_continuation_monad.mdwn +++ b/list_monad_as_continuation_monad.mdwn @@ -147,7 +147,7 @@ Yet we can still desire to go deeper, and see if the appropriate bind behavior emerges from the types, as it did for the previously considered monads. But we can't do that if we leave the list type as a primitive OCaml type. However, we know several ways of implementing -lists using just functions. In what follows, we're going to use type +lists using just functions. In what follows, we're going to use version 3 lists, the right fold implementation (though it's important and intriguing to wonder how things would change if we used some other strategy for implementing lists). These were the lists that made @@ -189,14 +189,14 @@ Generalizing to lists that contain any kind of element (not just So an `('a, 'b) list'` is a list containing elements of type `'a`, where `'b` is the type of some part of the plumbing. This is more general than an ordinary OCaml list, but we'll see how to map them -into OCaml lists soon. We don't need to fully grasp the role of the `'b`'s +into OCaml lists soon. We don't need to fully grasp the role of the `'b`s in order to proceed to build a monad: l'_unit (a : 'a) : ('a, 'b) list = fun a -> fun k z -> k a z -No problem. Arriving at bind is a little more complicated, but -exactly the same principles apply, you just have to be careful and -systematic about it. +Take an `'a` and return its v3-style singleton. No problem. Arriving at bind +is a little more complicated, but exactly the same principles apply, you just +have to be careful and systematic about it. l'_bind (u : ('a,'b) list') (f : 'a -> ('c, 'd) list') : ('c, 'd) list' = ...