Replace varset! with algol style :=

README.md

@@ -18,6 +18,10 @@ Implemented in mostly standard C99, dst runs on Windows, Linux and macOS.
 The few features that are not standard C (dynamic library loading, compiler specific optimizations),
 are fairly straight forward. Dst can be easily ported to new platforms.
 
+There is not much in the way of documentation yet because it is still a "personal project" and
+I don't want to freeze features prematurely. You can look in the examples directory, the test directory,
+or the file `src/compiler/boot.dst` to get a sense of what dst code looks like.
+
 ## Features
 
 * First class closures

examples/lazyseqs.dst

@@ -11,10 +11,11 @@
    state
    (do 
     (def n (f))
-    (varset! state n)
-    (varset! loaded true)
+    (:= state n)
+    (:= loaded true)
     n))))
 
+# This creates one more closure than necessary but oh well
 (defmacro delay 
  "Macro for lazy evaluation"
  [& forms] (tuple mem0 (apply1 tuple (array-concat ['fn []] forms))))

src/compiler/boot.dst

@@ -139,7 +139,7 @@ If no match is found, returns nil"
       :more (fn [] (< i len))
       :next (fn []
         (def ret (get x i))
-        (varset! i (+ i 1))
+        (:= i (+ i 1))
         ret) 
     })
   (def iters {
@@ -156,7 +156,7 @@ If no match is found, returns nil"
     :more (fn [] (< i top))
     :next (fn []
       (def ret i)
-      (varset! i (+ i 1))
+      (:= i (+ i 1))
       ret) 
   })
 
@@ -199,9 +199,9 @@ If no match is found, returns nil"
      (do
       (def n (next))
       (if (pred n) n (nextgood)))
-     (varset! alive false))))
- (defn nnext [] (def ret temp) (varset! temp (nextgood)) ret)
- (defn nmore [] (when isnew (varset! isnew false) (nnext)) alive)
+     (:= alive false))))
+ (defn nnext [] (def ret temp) (:= temp (nextgood)) ret)
+ (defn nmore [] (when isnew (:= isnew false) (nnext)) alive)
  {:more nmore :next nnext})
 
 (defmacro let [bindings & body]
@@ -213,7 +213,7 @@ If no match is found, returns nil"
    (array-push accum (tuple 'def 
                      (get head i)
                      (get head (+ 1 i))))
-   (varset! i (+ i 2)))
+   (:= i (+ i 2)))
   (array-push accum (tuple-prepend body 'do))
   (apply1 tuple accum))
 
@@ -223,7 +223,7 @@ If no match is found, returns nil"
     :more (fn [] lastkey)
     :next (fn []
         (def ret (tuple lastkey (get x lastkey)))
-        (varset! lastkey (next x lastkey))
+        (:= lastkey (next x lastkey))
         ret)
  })
 
@@ -233,7 +233,7 @@ If no match is found, returns nil"
     :more (fn [] lastkey)
     :next (fn []
         (def ret lastkey)
-        (varset! lastkey (next x lastkey))
+        (:= lastkey (next x lastkey))
         ret)
  })
 
@@ -243,7 +243,7 @@ If no match is found, returns nil"
     :more (fn [] lastkey)
     :next (fn []
         (def ret (get x lastkey))
-        (varset! lastkey (next x lastkey))
+        (:= lastkey (next x lastkey))
         ret)
  })
 
@@ -260,7 +260,7 @@ If no match is found, returns nil"
     (tuple 'def endsym end)
     (tuple 'while (tuple '< sym endsym)
      (tuple-prepend body 'do)
-     (tuple 'varset! sym (tuple '+ sym inc)))))
+     (tuple ':= sym (tuple '+ sym inc)))))
 
 (defmacro ->
  [x & forms]
@@ -311,7 +311,7 @@ If no match is found, returns nil"
       (pp seen buf k)
       (buffer-push-string buf " ")
       (pp seen buf v)
-      (varset! k (next a k))
+      (:= k (next a k))
       (when k (buffer-push-string buf " ")))
      (buffer-push-string buf end)))
    buf)
@@ -369,7 +369,7 @@ onvalue."
    (while (< 0 len)
       (buffer-clear buf)
       (chunks buf) 
-      (varset! len (length buf))
+      (:= len (length buf))
       (for [i 0 len]
         (yield (get buf i))))
    0)))
@@ -385,17 +385,17 @@ onvalue."
        (select (fiber-status chars)
         :new (parser-byte p (resume chars))
         :pending (parser-byte p (resume chars))
-        (varset! going false))))
+        (:= going false))))
     (when (not= :root (parser-status p))
      (onerr "parse" "unexpected end of source"))
     nil)))
  (defn more [] (if temp true 
   (do 
-   (varset! temp true)
-   (varset! tempval (resume f))
+   (:= temp true)
+   (:= tempval (resume f))
    going)))
  (defn next [] (if temp
-  (do (varset! temp nil) tempval)
+  (do (:= temp nil) tempval)
   (resume f)))
  {:more more :next next})
 (fn [env chunks onvalue onerr]

src/compiler/specials.c

@@ -615,6 +615,7 @@ DstSlot dstc_fn(DstFopts opts, DstAst *ast, int32_t argn, const Dst *argv) {
 
 /* Keep in lexographic order */
 static const DstSpecial dstc_specials[] = {
+    {":=", dstc_varset},
     {"ast-quote", dstc_astquote},
     {"def", dstc_def},
     {"do", dstc_do},
@@ -622,7 +623,6 @@ static const DstSpecial dstc_specials[] = {
     {"if", dstc_if},
     {"quote", dstc_quote},
     {"var", dstc_var},
-    {"varset!", dstc_varset},
     {"while", dstc_while}
 };
 

src/core/corelib.c

@@ -136,7 +136,7 @@ int dst_core_struct(DstArgs args) {
 
 int dst_core_fiber(DstArgs args) {
     DstFiber *fiber;
-    if (args.n < 1) return dst_throw(args, "expected at least one argument");
+    if (args.n < 1) return dst_throw(args, "expected at least 1 argument");
     if (!dst_checktype(args.v[0], DST_FUNCTION))
         return dst_throw(args, "expected a function");
     fiber = dst_fiber(dst_unwrap_function(args.v[0]), 64);

src/mainclient/init.dst

@@ -13,7 +13,7 @@
         (print "  -r Enter the repl after running all scripts")
         (exit 0))
   "v" (fn [] (print VERSION) (exit 0))
-  "r" (fn [] (varset! should-repl true))
+  "r" (fn [] (:= should-repl true))
 })
 
 (defn dohandler [n]
@@ -27,7 +27,7 @@
  (if (= "-" (string-slice arg 0 1))
   (dohandler (string-slice arg 1 2))
   (do
-   (varset! no-file false)
+   (:= no-file false)
    (import arg))))
 
 (when (or should-repl no-file)