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45 lines
1.1 KiB
Racket
45 lines
1.1 KiB
Racket
#lang racket/base
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(require (for-syntax racket/base))
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(provide macro-map macro-for-each)
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(define-syntax-rule (make-mappy-macro mappy-macro-name joining-proc ending-value)
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(define-syntax mappy-macro-name
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(syntax-id-rules ()
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;; convert quote form into list form
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[(_ macro-name (quote (items (... ...))))
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(mappy-macro-name macro-name (list items (... ...)))]
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;; catch this case first, because it would also match the next one
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[(_ macro-name (list item0))
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(joining-proc
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(macro-name item0) ending-value)]
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[(_ macro-name (list item0 items (... ...)))
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(joining-proc
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(macro-name item0)
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(mappy-macro-name macro-name (list items (... ...))))])))
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(make-mappy-macro macro-for-each begin (void))
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(make-mappy-macro macro-map cons '())
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(define-syntax-rule (add pair)
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(+ (car pair) (cdr pair)))
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;; this matches first case - why?
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(macro-for-each add (list (cons 12 20)))
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;(macro-map add (list 24 25 30))
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;(macro-map add '(24 25 30))
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;(macro-map-old add (list 24 25 30))
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;(macro-for-each add '(24 25 30))
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