Scheme (programming language): Difference between revisions

Revision as of 19:59, 17 May 2003

Revision as of 09:32, 18 May 2003

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== Language Elements ==

=== Comments ===

Comments are preceded by a [[semi-colon]] (;) and continue for the rest of the line.

=== Variables ===

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(factorial 5)

;; => 120

or a higher order function like ''map'' which applies a function to every element of a list

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(map (lambda (x) (* x x)) '(1 2 3 4))

;; => (1 4 9 16)

Another way to define loops is the ''named'' <code>named let</code> statement and the <code>do</code> statement. To use factorial and map again to illustrate both forms:

(define (factorial n)

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(factorial 5)

;; => 120

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(map (lambda (x) (* x x)) '(1 2 3 4))

;; => (1 4 9 16)

Please note that in both cases, the tail recursive version is preferrable.

=== Input/output ===

Scheme has the concept of ''ports'' to read from or to write to. Scheme defines three default ports, accessible with the functions: <code>current-input-port</code>, <code>current-output-port</code> and <code>current-error-port</code>.