Mainly worked on the rule matcher

Also fixed the name collector, and lambda parameters are no longer
resolved at parsing to support planned macro-based pattern matching.
The rule matcher clones a lot, the number of clones could be zero.

src/rule/rule_error.rs

@@ -0,0 +1,18 @@
+use std::{fmt, error::Error};
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum RuleError {
+    BadState(String),
+    ScalarVecMismatch(String)
+}
+
+impl fmt::Display for RuleError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::BadState(key) => write!(f, "Key {:?} not in match pattern", key),
+            Self::ScalarVecMismatch(key) =>
+                write!(f, "Key {:?} used inconsistently with and without ellipsis", key)
+        }
+    }
+}
+impl Error for RuleError {}