adding hash table literal syntax. closes issue #215.

this took about 20 minutes

j/table.j

@@ -97,10 +97,24 @@ type HashTable{K,V}
     HashTable(n) = (n = _tablesz(n);
                     new(Array(K,n), Array(V,n), IntSet(n+1), IntSet(n+1),
                         identity))
+    function HashTable(ks::Tuple, vs::Tuple)
+        n = length(ks)
+        h = HashTable{K,V}(n)
+        for i=1:n
+            h[ks[i]] = vs[i]
+        end
+        return h
+    end
 end
 HashTable() = HashTable(0)
 HashTable(n::Int) = HashTable{Any,Any}(n)
 
+# syntax entry point
+hashtable{K,V}(ks::(K...), vs::(V...)) = HashTable{K,V}    (ks, vs)
+hashtable{K}  (ks::(K...), vs::Tuple ) = HashTable{K,Any}  (ks, vs)
+hashtable{V}  (ks::Tuple , vs::(V...)) = HashTable{Any,V}  (ks, vs)
+hashtable     (ks::Tuple , vs::Tuple)  = HashTable{Any,Any}(ks, vs)
+
 hashindex(key, sz) = (long(hash(key)) & (sz-1)) + 1
 
 function rehash{K,V}(h::HashTable{K,V}, newsz)

src/julia-syntax.scm

@@ -707,18 +707,30 @@
 
    ;; cell array syntax
    (pattern-lambda (cell1d . args)
-		   (if (any (lambda (e) (and (pair? e) (eq? (car e) '...)))
-			    args)
-		       `(call (top cell_1d) ,@args)
-		       (let ((name (gensy)))
-			 `(block (= ,name (call (top Array) (top Any)
-						,(length args)))
-				 ,@(map (lambda (i elt)
-					  `(call (top arrayset) ,name ,(+ 1 i)
-						 ,elt))
-					(iota (length args))
-					args)
-				 ,name))))
+		   (cond ((any (lambda (e) (and (pair? e) (eq? (car e) '...)))
+			       args)
+			  `(call (top cell_1d) ,@args))
+			 ((any (lambda (e) (and (length= e 3)
+						(eq? (car e) '=>)))
+			       args)
+			  (if (not (every (lambda (e) (and (length= e 3)
+							   (eq? (car e) '=>)))
+					  args))
+			      (error "invalid hash table literal")
+			      `(call (top hashtable)
+				     (tuple ,@(map cadr  args))
+				     (tuple ,@(map caddr args)))))
+			 (else
+			  (let ((name (gensy)))
+			    `(block (= ,name (call (top Array) (top Any)
+						   ,(length args)))
+				    ,@(map (lambda (i elt)
+					     `(call (top arrayset) ,name
+						    ,(+ 1 i)
+						    ,elt))
+					   (iota (length args))
+					   args)
+				    ,name)))))
 
    (pattern-lambda (cell2d nr nc . args)
 		   (if (any (lambda (e) (and (pair? e) (eq? (car e) '...)))