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74 lines
2.1 KiB
Racket
74 lines
2.1 KiB
Racket
8 years ago
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#lang racket/base
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(require racket/class (for-syntax racket/base racket/syntax br/syntax) br/define)
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(provide (all-defined-out))
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;; js-style `push`, which appends to end of list
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(define-macro (push-end! ID THING)
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#'(set! ID (append ID (list THING))))
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(define-macro-cases increment!
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[(_ ID) #'(increment! ID 1)]
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[(_ ID EXPR)
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#'(begin (set! ID (+ ID EXPR)) ID)])
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(module+ test
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(define xs '(1 2 3))
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(push-end! xs 4)
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(check-equal? xs '(1 2 3 4)))
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(define-macro (+= ID THING) #'(begin (set! ID (+ ID THING)) ID))
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(define-macro (++ ID) #'(+= ID 1))
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(define-macro (-- ID) #'(+= ID -1))
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(define-macro (-= ID THING) #'(+= ID (- THING)))
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;; fancy number->string. bounds are checked, inexact integers are coerced.
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(define (number x)
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(unless (and (number? x) (< -1e21 x 1e21))
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(raise-argument-error 'number "valid number" x))
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(let ([x (/ (round (* x 1e6)) 1e6)])
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(number->string (if (integer? x)
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(inexact->exact x)
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x))))
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(module+ test
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(check-equal? (number 4.5) "4.5")
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(check-equal? (number 4.0) "4")
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(check-equal? (number 4) "4")
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(check-equal? (number -4) "-4"))
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(define-macro-cases ·
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[(_ X REF)
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#'(cond
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[(object? X) (with-handlers ([exn:fail:object? (λ (exn) (send X REF))])
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(get-field REF X))]
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[(hash? X) (hash-ref X 'REF #f)]
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[else (raise-argument-error '· (format "~a must be object or hash" 'X) X)])]
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[(_ X REF0 . REFS) #'(· (· X REF0) . REFS)])
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(define-macro (·map REF XS)
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#'(for/list ([x (in-list XS)]) (· x REF)))
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(module+ test
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(require rackunit)
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(define C
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(class object%
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(super-new)
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(field [foo 'field])
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(define/public (bar) 'method)
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(define/public (zam) (hasheq 'zoom 'hash))))
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(define h (hasheq 'bam (new C) 'foo 'hashlet))
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(define o (new C))
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(check-equal? (· o foo) 'field)
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(check-equal? (· o bar) 'method)
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(check-equal? (· o zam zoom) 'hash)
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(check-equal? (· h bam foo) 'field)
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(check-equal? (· h bam bar) 'method)
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(check-equal? (· h bam zam zoom) 'hash)
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(check-equal? (·map foo (list o h)) '(field hashlet)))
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