zip walks both lists in lockstep, truncating at the shorter. unzip
uses tuple-pattern destructuring on the recursive result.
let pairs = zip [1;2;3;4] [10;20;30;40] in
let (xs, ys) = unzip pairs in
List.fold_left (+) 0 xs * List.fold_left (+) 0 ys
= 10 * 100
= 1000
Exercises:
- tuple-cons patterns in match scrutinee: 'match (xs, ys) with'
- tuple constructor in return value: '(a :: la, b :: lb)'
- the iter-98 let-tuple destructuring: 'let (la, lb) = unzip rest'
53 baseline programs total.
