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.
33 lines
1.2 KiB
Racket
33 lines
1.2 KiB
Racket
9 years ago
|
#lang racket/base
|
||
|
|
(require (for-syntax racket/base br/syntax) br/define)
|
||
|
|
(provide (all-defined-out))
|
||
|
|
|
||
|
|
;; read "foo bar" the same way as "(foo bar)"
|
||
|
|
;; other "bar" is dropped, which is too astonishing
|
||
|
|
(define (string->datum str)
|
||
|
|
(let ([result (read (open-input-string (format "(~a)" str)))])
|
||
|
|
(if (= (length result) 1)
|
||
|
|
(car result)
|
||
|
|
result)))
|
||
|
|
|
||
|
|
(define-syntax format-datum
|
||
|
|
(λ(stx)
|
||
|
|
(syntax-case stx (quote datum)
|
||
|
|
[(_ (quote datum-template) arg ...)
|
||
|
|
#'(format-datum (datum datum-template) arg ...)]
|
||
|
|
[(_ (datum datum-template) arg ...)
|
||
|
|
(syntax-let ([#'format-string (format "~a" (syntax->datum #'datum-template))])
|
||
|
|
#'(string->datum (apply format format-string (list arg ...))))])))
|
||
|
|
|
||
|
|
|
||
|
|
(module+ test
|
||
|
|
(require rackunit)
|
||
|
|
(check-equal? (string->datum "foo") 'foo)
|
||
|
|
(check-equal? (string->datum "(foo bar)") '(foo bar))
|
||
|
|
(check-equal? (string->datum "foo bar") '(foo bar))
|
||
|
|
(check-equal? (string->datum "42") 42)
|
||
|
|
(check-equal? (format-datum '(~a-bar-~a) "foo" "zam") '(foo-bar-zam))
|
||
|
|
(check-equal? (format-datum (datum (~a-bar-~a)) "foo" "zam") '(foo-bar-zam))
|
||
|
|
(check-equal? (format-datum '~a "foo") 'foo)
|
||
|
|
(check-equal? (format-datum (datum ~a) "foo") 'foo))
|