hashes all the way

A microbenchmark reveals that alist lookup with assq never beats a hasheq lookup with hash-ref.
main
Matthew Butterick 3 years ago
parent dfd4dc9e74
commit 7a9ac1c43f

@ -26,7 +26,7 @@
(define/contract (quadify str)
(string? . -> . (listof quad?))
(for/list ([c (in-string str)])
(make-quad #f (list (cons 'char c)))))
(make-quad #f (make-quad-attrs (list (cons 'char c))))))
(define (make-compiler . passes)
(apply compose1 (reverse (cons quadify passes))))

@ -12,8 +12,8 @@
(define (quad? x)
(match x
[($quad (? quad-tag?)
(list (cons symbol? _) ...)
(list _ ...)) #true]
(? quad-attrs?)
(? quad-elems?)) #true]
[_ #false]))
(struct $quad (tag attrs elems) #:transparent #:mutable)
@ -24,9 +24,8 @@
[_ #false]))
(define set-quad-tag! set-$quad-tag!)
(define quad-attrs $quad-attrs)
(define (quad-attrs? x) (match x
[(list (cons (? symbol?) _) ...) #true]
[_ #false]))
(define (make-quad-attrs alist) (make-hasheq alist))
(define (quad-attrs? x) (hash-eq? x))
(define set-quad-attrs! set-$quad-attrs!)
(define quad-elems $quad-elems)
(define (quad-elems? x) (list? x))
@ -36,22 +35,21 @@
((quad-tag? quad-attrs?) #:rest quad-elems? . ->* . quad?)
($quad tag attrs elems))
(define (quad-ref q key [default-val #false]) (match (assq key (quad-attrs q))
[#false default-val]
[(cons _ val) val]))
(define (quad-ref q key [default-val #false])
(hash-ref (quad-attrs q) key default-val))
(define (quad-set! q key val)
(set-quad-attrs! q (cons (cons key val) (quad-attrs q))))
(hash-set! (quad-attrs q) key val))
(define-syntax (define-quad-field stx)
(syntax-case stx ()
[(_ FIELD)
(with-syntax ([GETTER (format-id stx "quad-~a" #'FIELD)]
[SETTER (format-id stx "set-quad-~a!" #'FIELD)])
#'(begin
(define (GETTER q) (quad-ref q 'FIELD))
(define (SETTER q val) (quad-set! q 'FIELD val))))]))
#'(begin
(define (GETTER q) (quad-ref q 'FIELD))
(define (SETTER q val) (quad-set! q 'FIELD val))))]))
(define-quad-field posn)
(define-quad-field char)
(define q (make-quad 'div '((hello . "world")) "fine"))
#;(define q (make-quad 'div (make-hasheq '((hello . "world"))) "fine"))
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