2d4f3e2ac9
The layer is now redundant, since everything left in "pkgs" is in the "racket-pkgs" category.
38 lines
1008 B
Racket
38 lines
1008 B
Racket
#lang scribble/doc
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@(require scribble/manual scribble/eval "guide-utils.rkt")
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@title{Named @racket[let]}
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A named @racket[let] is an iteration and recursion form. It uses the
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same syntactic keyword @racket[let] as for local binding, but an
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identifier after the @racket[let] (instead of an immediate open
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parenthesis) triggers a different parsing.
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@specform[
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(let proc-id ([arg-id init-expr] ...)
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body ...+)
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]
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A named @racket[let] form is equivalent to
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@racketblock[
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(letrec ([_proc-id (lambda (_arg-id ...)
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_body ...+)])
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(_proc-id _init-expr ...))
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]
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That is, a named @racket[let] binds a function identifier that is
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visible only in the function's body, and it implicitly calls the
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function with the values of some initial expressions.
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@defexamples[
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(define (duplicate pos lst)
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(let dup ([i 0]
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[lst lst])
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(cond
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[(= i pos) (cons (car lst) lst)]
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[else (cons (car lst) (dup (+ i 1) (cdr lst)))])))
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(duplicate 1 (list "apple" "cheese burger!" "banana"))
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]
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