2ea73fbc6a
* Switch srfi/1 and a few other packages (and optionals.ss) to scheme/base * Make srfi/1 etc reprovide `filter' from scheme/private/list * Organize a few modules that were unnecessarily providing a full language. * srfi/45 reprovides stuff from scheme/promise (see comments in "srfi/45/lazy.ss") svn: r8999
29 lines
958 B
Scheme
29 lines
958 B
Scheme
#lang scheme/base
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(provide feature-present? feature->require-clause)
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(define *feature-alist*
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'())
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(define (srfi-id? id)
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(regexp-match? #rx"^srfi-[0-9]+$" (symbol->string id)))
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(define (srfi-id->filename srfi-id)
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(regexp-replace #rx"^srfi-([0-9]+)$" (symbol->string srfi-id) "\\1/\\1.ss"))
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(define (srfi-id-present? srfi-id)
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(file-exists? (build-path (collection-path "srfi")
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(srfi-id->filename srfi-id))))
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(define (feature-present? id)
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(or (and (srfi-id? id) (srfi-id-present? id))
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(and (assq id *feature-alist*) #t)))
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(define (feature->require-clause id)
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(cond [(and (srfi-id? id) (srfi-id-present? id))
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(string->symbol (regexp-replace #rx"^srfi-([0-9]+)$"
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(symbol->string id)
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"srfi/\\1/\\1"))]
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[(assq id *feature-alist*) => cdr]
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[else (error 'feature->require-clause "unknown feature: ~e" id)]))
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