values lib

1 files changed, 66 insertions, 0 deletions

diff --git a/test/cas.scm b/test/cas.scm
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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))))
+