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84 lines
2.5 KiB
Plaintext
84 lines
2.5 KiB
Plaintext
10 years ago
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#lang scribble/manual
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@(require scribble/eval (for-label racket sugar))
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@(define my-eval (make-base-eval))
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@(my-eval `(require sugar))
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@title{Container}
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@defmodule[sugar/container]
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Type-neutral functions for getting elements out of a container, or testing membership.
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@defproc[
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(get
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[container (or/c list? vector? sequence? dict? string? symbol? path?)]
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[which any/c]
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[end_which (or/c (and/c integer? positive?) #f) #f])
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any/c]
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For a @racket[_container] that's a @racket[dict?], retrieve the element associated with the key @racket[_which]. Raise an error if the key doesn't exist.
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@examples[#:eval my-eval
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(get (make-hash '((a . 1) (b . 2) (c . 3))) 'b)
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(get (make-hash '((a . 1) (b . 2) (c . 3))) 'z)
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]
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For other @racket[_container] types — which are all sequence-like — retrieve the element located at @racket[_which]. Or if the optional @racket[_end_which] argument is provided, retrieve the elements from @racket[_which] to @racket[(sub1 _end_which)], inclusive (i.e., make a slice). Raise an error if @racket[_which] or @racket[_end_which] is out of bounds.
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@examples[#:eval my-eval
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(get '(0 1 2 3 4 5) 2)
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(get '(0 1 2 3 4 5) 2 4)
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(get '(0 1 2 3 4 5) 100)
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(get '(0 1 2 3 4 5) 2 100)
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(get (list->vector '(0 1 2 3 4 5)) 2)
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(get (list->vector '(0 1 2 3 4 5)) 2 4)
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(get "purple" 2)
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(get "purple" 2 4)
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(get 'purple 2)
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(get 'purple 2 4)
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]
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When @racket[_container] is a path, it's treated as a list of exploded path elements, not as a stringlike value.
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@examples[#:eval my-eval
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(get (string->path "/root/foo/bar/file.txt") 1)
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(get (string->path "/root/foo/bar/file.txt") 0 3)
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]
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To slice to the end of @racket[_container], use @racket[(len _container)] as the value of @racket[_end_which].
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@examples[#:eval my-eval
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(define xs '(0 1 2 3 4 5))
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(get xs 2 (len xs))
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(get (list->vector xs) 2 (len (list->vector xs)))
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(define color "purple")
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(get color 2 (len color))
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]
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@defproc[
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(in?
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[item any/c]
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[container (or/c list? vector? sequence? set? dict? string? symbol? path?)])
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boolean?]
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Return @racket[#t] if @racket[_item] is in @racket[_container], or @racket[#f] otherwise.
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@examples[#:eval my-eval
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(in? 2 '(0 1 2 3 4 5))
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(in? 'a '(0 1 2 3 4 5))
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(in? 2 (list->vector '(0 1 2 3 4 5)))
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(in? "pu" "purple")
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(in? "zig" "purple")
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(in? 'b (make-hash '((a . 1) (b . 2) (c . 3))))
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(in? 'z (make-hash '((a . 1) (b . 2) (c . 3))))
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]
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As with @racket[get], when @racket[_container] is a path, it's treated as a list of exploded path elements, not as a stringlike value.
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@examples[#:eval my-eval
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(in? "foo" (string->path "/root/foo/bar/file.txt"))
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(in? "zam" (string->path "/root/foo/bar/file.txt"))
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]
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