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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.
|#
(cond-expand
(chicken (import test r7rs))
(else (import (srfi 64))))
(load "../mcgoron.cond-thunk.srfi.210.compat.sld")
(load "../mcgoron.cond-thunk.sld")
(load "../mcgoron.cond-thunk.values.sld")
(import (mcgoron cond-thunk) (mcgoron cond-thunk values) (srfi 1))
(define function=> pair=>)
(define (mult=> form)
(cond-values
(after ((let (function=> form) => (head tail))
(when (eq? head '*)))
tail)))
(define (add=> form)
(cond-values
(after ((let (function=> form) => (head tail))
(when (eq? head '+)))
tail)))
(define (add? form)
(cond-thunk
(after ((let (add=> form) => (_)))
#t)
(else #f)))
(define (distribute form)
(cond-thunk
(after ((let (mult=> form) => (arguments)))
(let-values (((add others) (partition add? arguments)))
;; ADD is a list of addition clauses.
(let ((added-values (concatenate (map cdr add))))
(cons '+
(map (lambda (added-value)
(cons* '*
(distribute added-value)
others))
added-values)))))
(after ((let (function=> form) => (head arguments)))
(cons head (map distribute arguments)))
(else form)))
(test
"distribute1"
'(+ (* y x) (* z x))
(distribute '(* x (+ y z))))
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