improper lists, floats

1 files changed, 49 insertions, 24 deletions

diff --git a/prelude.scm b/prelude.scm
index 097ca64..cb22b18 100644
--- a/prelude.scm
+++ b/prelude.scm
@@ -34,8 +34,10 @@
 ;
 ; Others:
 ; __uniapply: Apply function to single argument
-; __null: A value that can only be passed to __unilambda. It cannot be
-;         bound to a top-level, or "set!", or added to a list.
+; <undefined>: A value that can only be passed to __unilambda. It cannot
+;              be bound to a top-level, or "set!", or added to a list.
+;              It can also be the parameter of a __unilambda, although
+;              it still cannot be used.
 ;
 ; Macros are functions that return an sexpr.
 
@@ -48,7 +50,7 @@
       ; (cdr (car (car args))) = (a)
       `((__unilambda ,(car (car (car args)))
                      (let ,(cdr (car args)) ,@body))
-        ,(car (cdr (car (car args))))
+        . ,(car (cdr (car (car args))))
        )
   )
  )
@@ -56,6 +58,20 @@
 
 (__define-macro let* let)
 
+; if and __unilambda only execute one statement. This uses Flatrate's
+; evaluation order (arguments first) and tail-call optimization to simulate
+; multiple statements.
+(__define-macro begin body
+ (let ((first (car body))
+       (rest (cdr body))
+      )
+  (if (null? rest)
+      first
+      `((__unilambda <undefined> (begin ,@rest)) . ,first)
+  )
+ )
+)
+
 (__define-macro __bindlambda
  (__unilambda l
   (let ((larg (car l))
@@ -66,7 +82,7 @@
        `(__unilambda larg
          (if (not (null? larg))
              (raise "incorrect number of arguments")
-             ,body
+             (begin ,@body)
          )
         )
        (let* ((argval (cons args))
@@ -90,12 +106,12 @@
        )
    (if (symbol? args)
        `(__unilambda ,args ,@body)
-        (let ((larg (gensym)))
-         (if (null? args)
-             `(__unilambda ,larg ,@body)
-             `(__bindlambda ,larg . body)
-         )
-        )
+       (if (null? args)
+           `(__unilambda <undefined> (begin ,@body))
+           (let ((larg (gensym)))
+             `(__bindlambda ,larg ,@body)
+           )
+       )
    )
   )
  )
@@ -110,23 +126,12 @@
          (tmpname (gensym))
         )
    `(__define-macro ,name
-     (lambda ,args ,body)
+     (lambda ,args ,@body)
     )
   )
  )
 )
 
-(define-macro (define name . body)
- (if (symbol? name)
-     `(__define ,name ,@body)
-     `(__define ,(car name) (lambda ,(cdr name) ,@body))
- )
-)
-
-(define-macro (begin . body)
- `((lambda () ,@body))
-)
-
 (define-macro (and . body)
  (if (null? body)
      1
@@ -157,13 +162,33 @@
             (val (car (cdr argval)))
             (rest (cdr args))
            )
-     `(let ((,arg __null))
-       (letrec ,rest (set! ,arg ,val) ,@body)
+     `(let ((,arg <undefined>))
+       (letrec ,rest (begin (set! ,arg ,val) ,@body))
       )
      )
  )
 )
 
+(define-macro (define name . body)
+ (if (symbol? name)
+     `(__define ,name ,@body)
+     (let ((fname (car name))
+           (args (cdr name))
+           (tmparg (gensym))
+          )
+      `(__define ,fname
+        (lambda ,tmparg
+         (letrec ((,fname (lambda ,args ,@body)))
+          (,fname . ,tmparg)
+         )
+       )
+     )
+    )
+ )
+)
+
+;;;;;;;;;;;;;; Standard Library ;;;;;;;;;;;;;;;;;;;
+
 ;; for a list of (v1 v2 ... vn)
 ;; runs (f vn (... (f v2 (f v1 start))))
 (define (foldl f start l)