From: ueno <ueno>
Date: Wed, 16 Aug 2000 16:26:45 +0000 (+0000)
Subject: Synch up with doodle.
X-Git-Tag: deisui-1_14_0-1~40
X-Git-Url: http://git.chise.org/gitweb/?a=commitdiff_plain;h=5165c04a7738977392a389373e3688482fae2614;p=elisp%2Fflim.git

Synch up with doodle.
---

diff --git a/closure.el b/closure.el
new file mode 100644
index 0000000..8220628
--- /dev/null
+++ b/closure.el
@@ -0,0 +1,66 @@
+(provide 'closure)
+
+;; closure is one of following forms.
+;;  FUNCTION
+;;  (WRAPPER FUNCTION FV1 . FVS)
+;;  (PARTIAL-ARGS CLOSURE)
+
+(defmacro closure-make (fun &rest fvs)
+  "Make a closure from a function FUN and free variables FVS.
+CAUTION: Do not assign to free variables."
+  (if (null fvs)
+      fun
+    (let* ((funv (make-symbol "funv"))
+	   (args (make-symbol "args")))
+      `(list
+	(lambda (,funv ,args ,@fvs)
+	  (apply ,funv ,args))
+	,fun
+	,@fvs))))
+
+(defmacro closure-partial-call (clo &rest args)
+  "Call partially."
+  `(list (list ,@args) ,clo))
+
+(defun closure-call (clo &rest args)
+  "Call closure."
+  (while
+      (and
+       (not (functionp clo))
+       (if (cddr clo)
+	   (progn
+	     (setq args (cons (cadr clo) (cons args (cddr clo)))
+		   clo (car clo))
+	     nil)
+	 t))
+    (setq args (append (car clo) args)
+	  clo (cadr clo)))
+  (apply clo args))
+
+(defun closure-compose (c1 c2)
+  "Compose C1 and C2.
+
+If either C1 or C2 is nil, another one is returned.
+If C1 and C2 is non-nil, C1 must be closure with one argument."
+  (cond
+   ((null c1) c2)
+   ((null c2) c1)
+   (t
+    (closure-make
+     (lambda (&rest args)
+       (closure-call c1 (apply 'closure-call c2 args)))
+     c1 c2))))
+
+'(
+
+(setq c1 (let ((a 1)) (closure-make (lambda (b) (+ a b)) a)))
+(closure-call c1 2) ; => 3
+
+(let ((a 1)) (setq plus1 (closure-make (lambda (b) (+ a b)) a)))
+(let ((a 2)) (setq plus2 (closure-make (lambda (b) (+ a b)) a)))
+(setq plus3 (closure-compose plus1 plus2))
+(closure-call plus3 4) ; => 7
+
+(closure-call (closure-partial-call (closure-partial-call '+ 1 2 3) 4 5 6) 7 8 9) ;=> 45
+
+)
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