Properly report syntax errors

pylisp/lisp.py

@@ -64,7 +64,12 @@ def run(self, s, mult=True):
             Lisp.eval = self.eval._orig
             Lisp.quasieval = self.quasieval._orig
             debug = -2
-        if isinstance(s, str): s = parser.parse(s)
+
+        try:
+            if isinstance(s, str): s = parser.parse(s)
+        except SyntaxError as e:
+            self.vars["signal"](self, ["error", "standard", "syntax"], *e.args)
+
         if not mult: s = [s]
         return map(lambda x: self.eval(self.preprocess(x)), s)[-1] if s else None
 

pylisp/sexp.py

@@ -219,6 +219,8 @@ def eat_function(s):
         if sexp:
             s = s.strip()
             body.append(sexp)
+        else:
+            raise SyntaxError("Unbalanced {:} notation")
 
     return ["fn", vars] + body, s[1:]
 

pylisp/shell.py

@@ -16,10 +16,11 @@
 l = lisp.Lisp()
 
 def handle_error(err):
-    print "Call stack:"
-    for i in l.call_stack:
-        print "\t%s" % builtin.str_(i)
-    print "Error:", err
+    if len(l.call_stack) > 1:
+        print "Call stack:"
+        for i in l.call_stack:
+            print "\t%s" % builtin.str_(i)
+    print err
     return ["bubble"]
 l.call_stack[0]._catches[("error",)] = handle_error
 
@@ -67,6 +68,9 @@ def input():
             sexps = list(lisp.parser.parse(s))
         except IndexError:
             s += raw_input("... > ") + "\n"
+        except SyntaxError as e:
+            print "(error standard syntax): " + str(e)
+            return input()
         else:
             break
     return s