giving a parse error for invalid utf-8 in bare string literals

fixes part of issue #10

doc/todo

@@ -749,6 +749,15 @@ and emit a type check if we inline
 
 -------------------------------------------------------------------------------
 
+table updates
+most general form is h[k] = f(get(h, k, default))
+
+more efficient implementation would be:
+i = findref(h,k)
+putref(h,i,f(getref(h,i,default)))
+
+-------------------------------------------------------------------------------
+
 issues 4/16/11
 
 clone(Array{Any,1}) matches both

src/ast.c

@@ -69,7 +69,7 @@ value_t fl_invoke_julia_macro(value_t *args, uint32_t nargs)
         JL_GC_POP();
         ios_printf(jl_current_output_stream(), "\n");
         jl_show(jl_exception_in_transit);
-        ios_printf(jl_current_output_stream(), "\n");
+        //ios_printf(jl_current_output_stream(), "\n");
         return fl_cons(symbol("error"), FL_NIL);
     }
     // protect result from GC, otherwise it could be freed during future

src/flisp/string.c

@@ -386,6 +386,14 @@ value_t fl_stringtonumber(value_t *args, uint32_t nargs)
     return n;
 }
 
+value_t fl_string_isutf8(value_t *args, u_int32_t nargs)
+{
+    argcount("string.isutf8", nargs, 1);
+    char *s = tostring(args[0], "string.isutf8");
+    size_t len = cv_len((cvalue_t*)ptr(args[0]));
+    return u8_isvalid(s, len) ? FL_T : FL_F;
+}
+
 static builtinspec_t stringfunc_info[] = {
     { "string", fl_string },
     { "string?", fl_stringp },
@@ -400,6 +408,7 @@ static builtinspec_t stringfunc_info[] = {
     { "string.reverse", fl_string_reverse },
     { "string.encode", fl_string_encode },
     { "string.decode", fl_string_decode },
+    { "string.isutf8", fl_string_isutf8 },
 
     { "char.upcase", fl_char_upcase },
     { "char.downcase", fl_char_downcase },

src/julia-parser.scm

@@ -1017,7 +1017,10 @@
 	   (let ((ps (parse-string-literal s)))
 	     (if (cdr ps)
 		 `(macrocall str ,(car ps))
-		 (unescape-string (car ps)))))
+		 (let ((str (unescape-string (car ps))))
+		   (if (not (string.isutf8 str))
+		       (error "invalid utf-8 sequence"))
+		   str))))
 
 	  ;; macro call
 	  ((eqv? t #\@)