experiment: viewport width and viewport height are accessible.

js-assembler/runtime-src/runtime.js

@@ -112,7 +112,7 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 		    var elt = MACHINE.env.pop();
 		    var outputPort = 
 			MACHINE.params.currentOutputPort;
-		    if (elt !== undefined) {
+		    if (elt !== VOID) {
 			outputPort.writeDomNode(MACHINE, toDomNode(elt, 'print'));
 			outputPort.writeDomNode(MACHINE, toDomNode("\n", 'print'));
 		    }
@@ -520,7 +520,24 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
     // are coded here; several of them (including call/cc) are injected by
     // the bootstrapping code.
     var Primitives = {};
-    Primitives['display'] = function(MACHINE) {
+
+    var installPrimitiveProcedure = function(name, arity, f) {
+        Primitives[name] = f;
+        Primitives[name].arity = arity;
+        Primitives[name].displayName = name;
+    };
+
+    var installPrimitiveConstant = function(name, v) {
+        Primitives[name] = v;
+    };
+
+
+    installPrimitiveConstant('pi', jsnums.pi);
+    installPrimitiveConstant('e', jsnums.e);
+
+    installPrimitiveProcedure(
+        'display', makeList(1, 2),
+        function(MACHINE) {
 	    var firstArg = MACHINE.env[MACHINE.env.length-1];
 	    var outputPort = MACHINE.params.currentOutputPort;
 	    if (MACHINE.argcount === 2) {
@@ -534,12 +551,11 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 	    }
 	    outputPort.writeDomNode(MACHINE, toDomNode(firstArg, 'display'));
             return VOID;
-    };
+        });
-    Primitives['display'].arity = makeList(1, 2);
-    Primitives['display'].displayName = 'display';
 
-
+    installPrimitiveProcedure(
-    Primitives['newline'] = function(MACHINE) {
+        'newline', makeList(0, 1),
+        function(MACHINE) {
 	    var outputPort = MACHINE.params.currentOutputPort;
 	    if (MACHINE.argcount === 1) { 
 	        testArgument(MACHINE,
@@ -552,12 +568,12 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 	    }
 	    outputPort.writeDomNode(MACHINE, toDomNode("\n", 'display'));
             return VOID;
-    };
+        });
-    Primitives['newline'].arity = makeList(0, 1);
-    Primitives['newline'].displayName = 'newline';
 
-
+    installPrimitiveProcedure(
-    Primitives['displayln'] = function(MACHINE){
+        'displayln',
+        makeList(1, 2),
+        function(MACHINE){
 	    var firstArg = MACHINE.env[MACHINE.env.length-1];
 	    var outputPort = MACHINE.params.currentOutputPort;
 	    if (MACHINE.argcount === 2) {
@@ -572,23 +588,26 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 	    outputPort.writeDomNode(MACHINE, toDomNode(firstArg, 'display'));
 	    outputPort.writeDomNode(MACHINE, toDomNode("\n", 'display'));
             return VOID;
-    };
+        });
-    Primitives['displayln'].arity = makeList(1, 2);
-    Primitives['displayln'].displayName = 'displayln';
 
 
-
+    installPrimitiveProcedure(
-    Primitives['current-print'] = function(MACHINE) {
+        'current-print',
+        makeList(0, 1),
+        function(MACHINE) {
+            if (MACHINE.argcount === 1) {
+                MACHINE.params['current-print'] = MACHINE.env[MACHINE.env.length - 1];
+                return VOID;
+            } else {
 	        return MACHINE.params['current-print'];
-    };
+            }
-    Primitives['current-print'].arity = makeList(0, 1);
+        });
-    Primitives['current-print'].displayName = "current-print";
 
-    Primitives['pi'] = jsnums.pi;
 
-    Primitives['e'] = jsnums.e;
+    installPrimitiveProcedure(
-
+        '=',
-    Primitives['='] = function(MACHINE) {
+        new ArityAtLeast(2),
+        function(MACHINE) {
 	    var firstArg = MACHINE.env[MACHINE.env.length-1];
 	    testArgument(MACHINE, 'number', isNumber, firstArg, 0, '=');
 	    for (var i = 0; i < MACHINE.argcount - 1; i++) {
@@ -604,11 +623,11 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 	        }
 	    }
 	    return true;
-    };
+        });
-    Primitives['='].arity = new ArityAtLeast(2);
-    Primitives['='].displayName = '=';
 
 
+    // TODO: use installPrimitiveProcedure for the rest...
+
     Primitives['<'] = function(MACHINE) {
 	var firstArg = MACHINE.env[MACHINE.env.length-1];
 	testArgument(MACHINE,
@@ -1161,6 +1180,24 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
 
 
 
+    // Extensions.  A small experiment.
+    installPrimitiveProcedure(
+        'viewport-width',
+        0,
+        function(MACHINE) {
+            return $(window).width();
+        });
+
+    installPrimitiveProcedure(
+        'viewport-height',
+        0,
+        function(MACHINE) {
+            return $(window).height();
+        });
+
+
+
+
 
 
     // recomputeGas: state number -> number
@@ -1342,6 +1379,9 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
     exports['currentMachine'] = new Machine();
     exports['invokeMains'] = invokeMains;
 
+
+    // installing new primitives
+    exports['installPrimitiveProcedure'] = installPrimitiveProcedure;
     exports['Primitives'] = Primitives;
     
     exports['ready'] = ready;
@@ -1417,5 +1457,7 @@ if(this['plt'] === undefined) { this['plt'] = {}; }
     exports['HaltError'] = HaltError;
 
 
+
+
     scope.link.announceReady('runtime');
 })(this['plt']);

lang/kernel.rkt

@@ -148,7 +148,7 @@
  display
  newline
 
- #;displayln
+;;  displayln
 
 ;;  current-print
 ;;  current-continuation-marks
@@ -394,6 +394,27 @@
 ;;  make-reader-graph
 ;;  make-placeholder
 ;;  placeholder-set!
-
-
  )
+
+
+
+
+
+(provide
+ ;; FIXME:
+ ;; Extensions: these may need to be hidden in a JavaScript-implemented module
+ viewport-width
+ viewport-height)
+
+
+
+;; viewport-width: -> natural
+;; The viewport width in pixels.
+(define (viewport-width)
+  (error 'viewport-width "Not available outside JavaScript context."))
+
+
+;; viewport-height: -> natural
+;; The viewport height in pixels.
+(define (viewport-height)
+  (error 'viewport-width "Not available outside JavaScript context."))