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Held: Wednesday, 20 February 2008
Summary: We consider procedures for that involve doing something with each element of a list. Along the way, we consider two key ideas of functional programming: higher-order programming and anonymous procedures .
Let's consider the steps involved in evaluating
(define x 5) (define y 3) (+ x y)
Now, let's try the following somewhat more complicated example.
(define x 5) (define y 7) (define fun (lambda (x) (* x y))) (fun 3)
map. The procedure for the second apprach is
(map function (list v1 v2 ... vn))
(list (function v1) (function v2) (function v3) ... (function vn))
Let's return to the examples. What happens if we write
(define triple (lambda (x) (* x 3)))) (map triple (list 1 2 3))
As we'll see, the interpreter substitutes the lambda expression for
triple. We can do the same.
(map (lambda (x) (* x 3)) (list 1 2 3))
(foreach! function (list v1 v2 .... vn))
(function v1) (function v2) ... (function vn) null
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