27 lines
934 B
Scheme
27 lines
934 B
Scheme
(module bindings mzscheme
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(require (lib "list.ss"))
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(provide extract-binding/single
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extract-bindings
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exists-binding?)
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; extract-binding/single : sym (listof (cons str str)) -> str
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(define (extract-binding/single name bindings)
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(define lst (extract-bindings name bindings))
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(cond
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[(empty? lst)
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(error 'extract-binding/single "~e not found in ~e" name bindings)]
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[(empty? (rest lst))
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(first lst)]
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[else
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(error 'extract-binding/single "~e occurs multiple times in ~e" name bindings)]))
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; extract-bindings : sym (listof (cons str str)) -> (listof str)
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(define (extract-bindings name bindings)
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(map cdr (filter (lambda (x) (equal? name (car x))) bindings)))
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; exists-binding? : sym (listof (cons sym str)) -> bool
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; for checkboxes
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(define (exists-binding? name bindings)
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(if (assq name bindings)
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#t
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#f))) |