From b55563aa31950b6d5c27f1baf90338d1339ff5ee Mon Sep 17 00:00:00 2001 From: jim Date: Sat, 14 Feb 2015 12:41:45 -0500 Subject: [PATCH] add map2 extra credit --- exercises/assignment3.mdwn | 3 +++ 1 file changed, 3 insertions(+) diff --git a/exercises/assignment3.mdwn b/exercises/assignment3.mdwn index b76e38cd..a6d31730 100644 --- a/exercises/assignment3.mdwn +++ b/exercises/assignment3.mdwn @@ -18,6 +18,9 @@ 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. +(Want a further challenge? Define `map2` in the Lambda Calculus, using our right-fold encoding for lists, where `map2 g [a, b, c] [d, e, f]` should evaluate to `[g a d, g b e, g c f]`. Doing this will require drawing on a number of different tools we've developed, including the strategy discussed this week for defining `tail`. Purely extra credit.) + + ## Numbers -- 2.11.0