From 5d5611c407171dd0d2461f6af0cfe0016690d9f8 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 8 Feb 2016 23:45:00 -0500
Subject: [PATCH] WIP

---
 scheme/lazy.sld | 122 ++++++++++++++++++++++++++----------------------
 1 file changed, 66 insertions(+), 56 deletions(-)

diff --git a/scheme/lazy.sld b/scheme/lazy.sld
index 93ba53eb..078ccede 100644
--- a/scheme/lazy.sld
+++ b/scheme/lazy.sld
@@ -5,66 +5,76 @@
     force 
     delay-force 
     make-promise 
-    promise?)
+    ;promise?
+  )
   (begin
-    (define (make-promise x)
-      (delay x))
-  ;)
-  ;(begin
-    (define (promise? x)
-      (and (pair? x)
-           (null? (cdr x))
-           (pair? (car x))
-           (or (eq? #t (caar x))
-               (and (eq? #f (caar x))
-                    (procedure? (cdar x))))))
+;    (define (make-promise x)
+;      (delay x))
+;  ;)
+;  ;(begin
+;    (define (promise? x)
+;      (and (pair? x)
+;           (null? (cdr x))
+;           (pair? (car x))
+;           (or (eq? #t (caar x))
+;               (and (eq? #f (caar x))
+;                    (procedure? (cdar x))))))
+;
+;  (define-syntax delay-force
+;    (er-macro-transformer
+;     (lambda (expr rename compare)
+;       `(,(rename 'promise) #f (,(rename 'lambda) () ,(cadr expr))))))
+;
+;  (define-syntax delay
+;    (er-macro-transformer
+;     (lambda (expr rename compare)
+;       `(,(rename 'delay-force) (,(rename 'promise) #t ,(cadr expr))))))
+;
+;  (define (promise done? proc)
+;    (list (cons done? proc)))
+;  (define (promise-done? x) (car (car x)))
+;  (define (promise-value x) (cdr (car x)))
+;  (define (promise-update! new old)
+;    (set-car! (car old) (promise-done? new))
+;    (set-cdr! (car old) (promise-value new))
+;    (set-car! new (car old)))
+;  (define (force promise)
+;    (if (promise-done? promise)
+;        (promise-value promise)
+;        (let ((promise* ((promise-value promise))))
+;          (if (not (promise-done? promise))
+;            (promise-update! promise* promise))
+;          (force promise))))))
 
-  (define-syntax delay-force
-    (er-macro-transformer
-     (lambda (expr rename compare)
-       `(,(rename 'promise) #f (,(rename 'lambda) () ,(cadr expr))))))
+  ;; Delayed evaluation functions from husk
+  (define force
+      (lambda (object)
+        (object)))
 
   (define-syntax delay
     (er-macro-transformer
      (lambda (expr rename compare)
-       `(,(rename 'delay-force) (,(rename 'promise) #t ,(cadr expr))))))
+       `(make-promise (lambda () ,(cadr expr))))))
+  (define-syntax delay-force
+    (er-macro-transformer
+     (lambda (expr rename compare)
+       `(make-promise (lambda () ,(cadr expr))))))
+  ;(define-syntax delay 
+  ;  (syntax-rules () 
+  ;    ((delay expression)
+  ;     (make-promise (lambda () expression)))))
 
-  (define (promise done? proc)
-    (list (cons done? proc)))
-  (define (promise-done? x) (car (car x)))
-  (define (promise-value x) (cdr (car x)))
-  (define (promise-update! new old)
-    (set-car! (car old) (promise-done? new))
-    (set-cdr! (car old) (promise-value new))
-    (set-car! new (car old)))
-  (define (force promise)
-    (if (promise-done? promise)
-        (promise-value promise)
-        (let ((promise* ((promise-value promise))))
-          (if (not (promise-done? promise))
-            (promise-update! promise* promise))
-          (force promise))))))
-
-;; Delayed evaluation functions from husk
-;(define force
-;    (lambda (object)
-;      (object)))
-;
-;(define-syntax delay 
-;  (syntax-rules () 
-;    ((delay expression)
-;     (make-promise (lambda () expression)))))
-;
-;(define make-promise
-;  (lambda (proc)
-;    (let ((result-ready? #f)
-;          (result #f))
-;      (lambda ()
-;        (if result-ready? 
-;            result
-;            (let ((x (proc)))
-;              (if result-ready?
-;                  result
-;                  (begin (set! result x)
-;                         (set! result-ready? #t)
-;                         result))))))))
+  (define make-promise
+    (lambda (proc)
+      (let ((result-ready? #f)
+            (result #f))
+        (lambda ()
+          (if result-ready? 
+              result
+              (let ((x (proc)))
+                (if result-ready?
+                    result
+                    (begin (set! result x)
+                           (set! result-ready? #t)
+                           result))))))))
+))