You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
24 lines
756 B
Racket
24 lines
756 B
Racket
8 years ago
|
#lang racket/base
|
||
|
(require (for-syntax racket/base) br/define)
|
||
|
(provide (all-defined-out))
|
||
|
|
||
|
(define-macro (define-case-macro ID PRED)
|
||
|
#'(define-syntax (ID stx)
|
||
|
(syntax-case stx ()
|
||
|
[(_ test-val
|
||
|
[(match-vals) . result] (... ...)
|
||
|
[else . else-result])
|
||
|
#'(cond
|
||
|
[(PRED test-val '(match-vals)) . result] (... ...)
|
||
|
[else . else-result])]
|
||
|
[(_ test-val
|
||
|
match-clause (... ...))
|
||
|
#'(ID test-val
|
||
|
match-clause (... ...)
|
||
|
[else (error 'ID "no match")])])))
|
||
|
|
||
|
;; like case but strictly uses `eq?` comparison (as opposed to `equal?`)
|
||
|
(define-case-macro caseq memq)
|
||
|
|
||
|
;; `eqv?` is OK for chars (same as `char=?`)
|
||
|
(define-case-macro casev memv)
|