From: Jim Pryor
Date: Tue, 26 Oct 2010 14:29:02 +0000 (-0400)
Subject: ass5: prime lift,bind,add
X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=6ea619babdb3656bf940636bd6823c6a2b8697c1
ass5: prime lift,bind,add
Signed-off-by: Jim Pryor
---
diff --git a/assignment5.mdwn b/assignment5.mdwn
index 02c0ac4d..5a2a488c 100644
--- a/assignment5.mdwn
+++ b/assignment5.mdwn
@@ -127,19 +127,19 @@ Baby monads
-----------
Read the lecture notes for week 6, then write a
-function `lift` that generalized the correspondence between + and
-`add`: that is, `lift` takes any two-place operation on integers
+function `lift'` that generalized the correspondence between + and
+`add'`: that is, `lift'` takes any two-place operation on integers
and returns a version that takes arguments of type `int option`
instead, returning a result of `int option`. In other words,
-`lift` will have type
+`lift'` will have type
(int -> int -> int) -> (int option) -> (int option) -> (int option)
-so that `lift (+) (Some 3) (Some 4)` will evalute to `Some 7`.
+so that `lift' (+) (Some 3) (Some 4)` will evalute to `Some 7`.
Don't worry about why you need to put `+` inside of parentheses.
-You should make use of `bind` in your definition of `lift`:
+You should make use of `bind'` in your definition of `lift'`:
- let bind (x: int option) (f: int -> (int option)) =
+ let bind' (x: int option) (f: int -> (int option)) =
match x with None -> None | Some n -> f n;;