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#| Copyright 2024 Peter McGoron
|
| Licensed under the Apache License, Version 2.0 (the "License");
|
| you may not use this file except in compliance with the License.
| You may obtain a copy of the License at
|
| http://www.apache.org/licenses/LICENSE-2.0
|
| Unless required by applicable law or agreed to in writing, software
| distributed under the License is distributed on an "AS IS" BASIS,
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
| See the License for the specific language governing permissions and
| limitations under the License.
|#
(define-syntax cond-thunk
(syntax-rules (else)
((cond-thunk expr ... (else body ...))
(cond
(expr => (lambda (x) (x)))
...
(else body ...)))
((cond-thunk expr ...)
(cond-thunk expr ... (else #f)))))
(define any-thunk
(letrec ((loop
(lambda (thunks else-thunk)
(if (null? thunks)
(else-thunk)
(let* ((thunk (car thunks))
(result (thunk)))
(if (not result)
(loop (cdr thunks))
(result)))))))
(case-lambda
((thunks) (loop thunks (lambda () #f)))
((thunks else-thunk) (loop thunks else-thunk)))))
(define-syntax when-ct
(syntax-rules ()
((when-ct conditional body ...)
(if conditional
(lambda () body ...)
#f))))
(define-syntax lambda-ct
(syntax-rules ()
((lambda-ct formal conditional body ...)
(lambda formal (when-ct conditional body ...)))))
(define-syntax define-ct
(syntax-rules ()
((define-ct (name . formal) conditional body ...)
(define name
(lambda-ct formal conditional body ...)))))
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