fb29a2498e
Add convenience lib for unstable docs.
Add char support to format-{id,symbol}
Add unstable/sequence library.
svn: r16789
46 lines
1.3 KiB
Scheme
46 lines
1.3 KiB
Scheme
#lang scheme/base
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(require (for-syntax scheme/base))
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(provide in-syntax in-pairs in-sequence-forever sequence-lift)
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(define-sequence-syntax in-syntax
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(lambda () #'(lambda (e) (in-list (syntax->list e))))
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(lambda (stx)
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(syntax-case stx ()
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[[ids (_ arg)]
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#'[ids (in-list (syntax->list arg))]])))
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(define (in-pairs seq)
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(make-do-sequence
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(lambda ()
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(let-values ([(more? gen) (sequence-generate seq)])
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(values (lambda (e) (let ([e (gen)]) (values (car e) (cdr e))))
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(lambda (_) #t)
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#t
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(lambda (_) (more?))
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(lambda _ #t)
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(lambda _ #t))))))
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(define (in-sequence-forever seq val)
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(make-do-sequence
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(lambda ()
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(let-values ([(more? gen) (sequence-generate seq)])
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(values (lambda (e) (let ([e (if (more?) (gen) val)]) e))
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(lambda (_) #t)
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#t
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(lambda (_) #t)
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(lambda _ #t)
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(lambda _ #t))))))
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(define (sequence-lift f seq)
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(make-do-sequence
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(lambda ()
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(let-values ([(more? gen) (sequence-generate seq)])
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(values (lambda (e) (compose f gen))
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(lambda (_) #t)
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#t
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(lambda (_) (more?))
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(lambda _ #t)
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(lambda _ #t))))))
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