ac26fe7554
Also, updates some of the mzlib files to point at `racket/*' libraries rather than to `scheme/*' ones.
72 lines
2.6 KiB
Racket
72 lines
2.6 KiB
Racket
#lang scribble/manual
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@(require scribble/eval "utils.rkt" (for-label scheme unstable/hash))
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@(define the-eval (make-base-eval))
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@(the-eval '(require unstable/hash))
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@title{Hash Tables}
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@defmodule[unstable/hash]
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@unstable[@author+email["Carl Eastlund" "cce@racket-lang.org"]]
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This module provides tools for manipulating hash tables.
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@defproc[(hash-union [h0 (and/c hash? hash-can-functional-set?)]
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[h hash?] ...
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[#:combine combine
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(-> any/c any/c any/c)
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(lambda _ (error 'hash-union ...))]
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[#:combine/key combine/key
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(-> any/c any/c any/c any/c)
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(lambda (k a b) (combine a b))])
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(and/c hash? hash-can-functional-set?)]{
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Computes the union of @racket[h0] with each hash table @racket[h] by functional
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update, adding each element of each @racket[h] to @racket[h0] in turn. For each
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key @racket[k] and value @racket[v], if a mapping from @racket[k] to some value
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@racket[v0] already exists, it is replaced with a mapping from @racket[k] to
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@racket[(combine/key k v0 v)].
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@defexamples[
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#:eval the-eval
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(hash-union (make-immutable-hash '([1 . one])) (make-immutable-hash '([2 . two])) (make-immutable-hash '([3 . three])))
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(hash-union (make-immutable-hash '([1 . (one uno)] [2 . (two dos)]))
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(make-immutable-hash '([1 . (ein une)] [2 . (zwei deux)]))
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#:combine/key (lambda (k v1 v2) (append v1 v2)))
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]
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}
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@defproc[(hash-union! [h0 (and/c hash? hash-mutable?)]
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[h hash?] ...
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[#:combine combine
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(-> any/c any/c any/c)
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(lambda _ (error 'hash-union ...))]
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[#:combine/key combine/key
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(-> any/c any/c any/c any/c)
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(lambda (k a b) (combine a b))])
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void?]{
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Computes the union of @racket[h0] with each hash table @racket[h] by mutable
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update, adding each element of each @racket[h] to @racket[h0] in turn. For each
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key @racket[k] and value @racket[v], if a mapping from @racket[k] to some value
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@racket[v0] already exists, it is replaced with a mapping from @racket[k] to
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@racket[(combine/key k v0 v)].
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@defexamples[
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#:eval the-eval
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(define h (make-hash))
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h
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(hash-union! h (make-immutable-hash '([1 . (one uno)] [2 . (two dos)])))
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h
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(hash-union! h
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(make-immutable-hash '([1 . (ein une)] [2 . (zwei deux)]))
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#:combine/key (lambda (k v1 v2) (append v1 v2)))
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h
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]
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}
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@(close-eval the-eval)
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