78 lines
2.0 KiB
Scheme
78 lines
2.0 KiB
Scheme
|
|
||
|
|
(library (ikarus.sort)
|
||
|
|
(export list-sort vector-sort)
|
||
|
|
(import
|
||
|
|
(ikarus system $fx)
|
||
|
|
(except (ikarus) list-sort vector-sort))
|
||
|
|
|
||
|
|
|
||
|
|
(define (merge1 <? a1 ls1 ls2)
|
||
|
|
(cond
|
||
|
|
[(null? ls2) ls1]
|
||
|
|
[else
|
||
|
|
(let ([a2 (car ls2)])
|
||
|
|
(cond
|
||
|
|
[(<? a2 a1)
|
||
|
|
(cons a2 (merge1 <? a1 ls1 (cdr ls2)))]
|
||
|
|
[else
|
||
|
|
(cons a1 (merge2 <? a2 (cdr ls1) ls2))]))]))
|
||
|
|
|
||
|
|
(define (merge2 <? a2 ls1 ls2)
|
||
|
|
(cond
|
||
|
|
[(null? ls1) ls2]
|
||
|
|
[else
|
||
|
|
(let ([a1 (car ls1)])
|
||
|
|
(cond
|
||
|
|
[(<? a2 a1)
|
||
|
|
(cons a2 (merge1 <? a1 ls1 (cdr ls2)))]
|
||
|
|
[else
|
||
|
|
(cons a1 (merge2 <? a2 (cdr ls1) ls2))]))]))
|
||
|
|
|
||
|
|
(define (merge <? ls1 ls2)
|
||
|
|
(cond
|
||
|
|
[(null? ls2) ls1]
|
||
|
|
[else
|
||
|
|
(let ([a1 (car ls1)] [a2 (car ls2)])
|
||
|
|
(cond
|
||
|
|
[(<? a2 a1)
|
||
|
|
(cons a2 (merge1 <? a1 ls1 (cdr ls2)))]
|
||
|
|
[else
|
||
|
|
(cons a1 (merge2 <? a2 (cdr ls1) ls2))]))]))
|
||
|
|
|
||
|
|
(define (sort-head <? ls n)
|
||
|
|
(cond
|
||
|
|
[($fx= n 0) (values '() ls)]
|
||
|
|
[($fx= n 1)
|
||
|
|
(values (cons (car ls) '()) (cdr ls))]
|
||
|
|
[else
|
||
|
|
(let-values ([(sorted-head tail)
|
||
|
|
(sort-head <? ls ($fxsra n 1))])
|
||
|
|
(let-values ([(sorted-tail tail)
|
||
|
|
(sort-head <? tail ($fx- n ($fxsra n 1)))])
|
||
|
|
(values (merge <? sorted-head sorted-tail) tail)))]))
|
||
|
|
|
||
|
|
(define (sort-tail <? ls n)
|
||
|
|
(cond
|
||
|
|
[($fx<= n 1) ls]
|
||
|
|
[else
|
||
|
|
(let-values ([(sorted-head tail)
|
||
|
|
(sort-head <? ls ($fxsra n 1))])
|
||
|
|
(merge <? sorted-head (sort-tail <? tail ($fx- n ($fxsra n 1)))))]))
|
||
|
|
|
||
|
|
(define (list-sort <? ls)
|
||
|
|
(unless (procedure? <?)
|
||
|
|
(error 'list-sort "~s is not a procedure" <?))
|
||
|
|
(sort-tail <? ls (length ls)))
|
||
|
|
|
||
|
|
(define (vector-sort <? v)
|
||
|
|
;;; FIXME: improve
|
||
|
|
(unless (procedure? <?)
|
||
|
|
(error 'vector-sort "~s is not a procedure" <?))
|
||
|
|
(unless (vector? v)
|
||
|
|
(error 'vector-sort "~s is not a vector" v))
|
||
|
|
(list->vector
|
||
|
|
(sort-tail <? (vector->list v) (vector-length v))))
|
||
|
|
)
|
||
|
|
|
||
|
|
|