55 lines
2.2 KiB
Scheme
55 lines
2.2 KiB
Scheme
;;; Copyright (C) Peter McGoron 2024
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;;; This program is free software: you can redistribute it and/or modify
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;;; it under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation, version 3 of the License.
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;;;
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;;; This program is distributed in the hope that it will be useful,
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;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with this program. If not, see <https://www.gnu.org/licenses/>.
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;;;
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;;; Simple COND-EXPAND using SYNTAX-RULES. Designed for chez.
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(define-syntax cond-expand-conditional
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(syntax-rules (and or not chez r6rs)
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;; Defined keywords
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((cond-expand-conditional chez execute alt) execute)
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((cond-expand-conditional r6rs execute alt) execute)
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;; Conditional statements: AND
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((cond-expand-conditional (and e1 e2 ...) execute alt)
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(cond-expand-conditional e1
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(cond-expand-conditional
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(and e2 ...)
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execute
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alt)
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alt))
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((cond-expand-conditional (and) execute alt) execute)
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;; OR
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((cond-expand-conditional (or e1 e2 ...) execute alt)
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(cond-expand-conditional e1 execute
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(cond-expand-conditional
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(or e2 ...) execute alt)))
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((cond-expand-conditional (or) execute alt) alt)
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;; NOT
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((cond-expand-conditional (not e) execute alt)
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(cond-expand-conditional e alt execute))
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;; All other conditions
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((cond-expand-conditional unknown execute alt) alt)))
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(define-syntax cond-expand
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(syntax-rules (else)
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((cond-expand (else evaluated ...)) (begin evaluated ...))
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((cond-expand (conditional evaluated ...) rest ...)
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(cond-expand-conditional conditional
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(begin evaluated ...)
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(cond-expand rest ...)))))
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(define %r6rs-error error)
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(define (error . rest)
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(apply %r6rs-error (cons "UNSLISP" rest)))
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