From: Chris Barker Date: Sun, 31 Oct 2010 14:18:27 +0000 (-0400) Subject: edits X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=80761171a28334806b396982c66e7f8ff4267eec edits --- diff --git a/week7.mdwn b/week7.mdwn index 9f139c16..52bc8eb5 100644 --- a/week7.mdwn +++ b/week7.mdwn @@ -48,24 +48,24 @@ that provides at least the following three elements: use a container metaphor: if `x` has type `int option`, then `x` is a box that (may) contain an integer. - type 'a option = None | Some of 'a;; + `type 'a option = None | Some of 'a;;` * A way to turn an ordinary value into a monadic value. In Ocaml, we did this for any integer n by mapping an arbitrary integer `n` to the option `Some n`. To be official, we can define a function called unit: - let unit x = Some x;; - val unit : 'a -> 'a option = + `let unit x = Some x;;` + + `val unit : 'a -> 'a option = ` So `unit` is a way to put something inside of a box. * A bind operation (note the type): -
-     let bind m f = match m with None -> None | Some n -> f n;;
-     val bind : 'a option -> ('a -> 'b option) -> 'b option = 
-
+ `let bind m f = match m with None -> None | Some n -> f n;;` + + `val bind : 'a option -> ('a -> 'b option) -> 'b option = ` `bind` takes two arguments (a monadic object and a function from ordinary objects to monadic objects), and returns a monadic @@ -77,7 +77,7 @@ that provides at least the following three elements: Then the second argument uses `x` to compute a new monadic value. Conceptually, then, we have - let bind m f = (let x = unwrap m in f x);; + `let bind m f = (let x = unwrap m in f x);;` The guts of the definition of the `bind` operation amount to specifying how to unwrap the monadic object `m`. In the bind