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