Add "!" syntatic form - a bit like the single quote, but !(a b c) d => !(a b c d). Useful for like !(let a 1) (+ a 3) or w/e. Break out some of the infinate nesting"

kr/src/grammar.lalrpop

@@ -9,6 +9,9 @@ pub Term: Form = {
     SYM => Form::Symbol(<>.to_owned()),
 	"(" <ListInside?> ")" => <>.unwrap_or(Form::Nil),
 	"'" <Term> => Form::Pair(Rc::new(Form::Symbol("quote".to_owned())), Rc::new(Form::Pair(Rc::new(<>), Rc::new(Form::Nil)))),
+	"!" <h: Term> <t: Term> => {
+        h.append(Rc::new(t)).unwrap()
+     },
 };
 ListInside: Form = {
 	<Term> => Form::Pair(Rc::new(<>), Rc::new(Form::Nil)),
@@ -20,6 +23,7 @@ match {
     ")",
     ".",
     "'",
+    "!",
     r"[0-9]+"                              => NUM,
     r"[a-zA-Z+*/_=?%&|^-][\w+*/=_?%&|^-]*" => SYM,
     r"(;[^\n]*\n)|\s+"                     => { }