From: jim Date: Sat, 14 Feb 2015 14:52:37 +0000 (-0500) Subject: tweak X-Git-Url: http://lambda.jimpryor.net/git/gitweb.cgi?p=lambda.git;a=commitdiff_plain;h=718e30fba02b10ced1bdd08c751cf83e28009846 tweak --- diff --git a/exercises/assignment3.mdwn b/exercises/assignment3.mdwn index 9dfece9a..b76e38cd 100644 --- a/exercises/assignment3.mdwn +++ b/exercises/assignment3.mdwn @@ -16,7 +16,7 @@ 7. Continuing to encode lists in terms of their left-folds, how should we write `head`? This is challenging. [[Here is a solution|assignment3 hint2]], if you need help. -8. Suppose you have two lists of integers, `left` and `right`. You want to determine whether those lists are equal, that is, whether they have all the same members in the same order. How would you implement such a list comparison? You can write it in Scheme or Kapulet using `letrec`, or if you want more of a challenge, in the Lambda Calculus using your preferred encoding for lists. If you write it in Scheme, don't rely on the built-in comparison operator `equal?` (nor on the operator `eqv?`, which won't do what you expect with lists). You can however rely on the comparison operator `=` which accepts only number arguments. If you write it in the Lambda Calculus, you can use your implementation of `leq`, requested below, to write an equality operator for Church-encoded numbers. [[Here is a hint|assignment3 hint3]], if you need it. +8. Suppose you have two lists of integers, `left` and `right`. You want to determine whether those lists are equal, that is, whether they have all the same members in the same order. How would you implement such a list comparison? You can write it in Scheme or Kapulet using `letrec`, or if you want more of a challenge, in the Lambda Calculus using your preferred encoding for lists. If you write it in Scheme, don't rely on applying the built-in comparison operator `equal?` to the lists themselves. (Nor on the operator `eqv?`, which might not do what you expect.) You can however rely on the comparison operator `=` which accepts only number arguments. If you write it in the Lambda Calculus, you can use your implementation of `leq`, requested below, to write an equality operator for Church-encoded numbers. [[Here is a hint|assignment3 hint3]], if you need it. ## Numbers