Preparation for sharing

- rustfmt
- clippy
- comments
- README

src/rule/rule_error.rs

@@ -1,36 +1,35 @@
 use std::fmt;
 
-use crate::interner::{Token, InternedDisplay, Interner};
+use crate::interner::{InternedDisplay, Interner, Tok};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum RuleError {
-  Missing(Token<String>),
-  TypeMismatch(Token<String>),
+  Missing(Tok<String>),
+  TypeMismatch(Tok<String>),
   /// Multiple occurences of a placeholder in a pattern are no longer
   /// supported.
-  Multiple(Token<String>),
-  VecNeighbors(Token<String>, Token<String>),
+  Multiple(Tok<String>),
+  VecNeighbors(Tok<String>, Tok<String>),
 }
 
 impl InternedDisplay for RuleError {
   fn fmt_i(&self, f: &mut fmt::Formatter<'_>, i: &Interner) -> fmt::Result {
     match *self {
-      Self::Missing(key) => write!(f,
-        "Key {:?} not in match pattern",
-        i.r(key)
-      ),
-      Self::TypeMismatch(key) => write!(f,
+      Self::Missing(key) =>
+        write!(f, "Key {:?} not in match pattern", i.r(key)),
+      Self::TypeMismatch(key) => write!(
+        f,
         "Key {:?} used inconsistently with and without ellipsis",
         i.r(key)
       ),
-      Self::Multiple(key) => write!(f,
-        "Key {:?} appears multiple times in match pattern",
-        i.r(key)
-      ),
-      Self::VecNeighbors(left, right) => write!(f,
+      Self::Multiple(key) =>
+        write!(f, "Key {:?} appears multiple times in match pattern", i.r(key)),
+      Self::VecNeighbors(left, right) => write!(
+        f,
         "Keys {:?} and {:?} are two vectorials right next to each other",
-        i.r(left), i.r(right)
-      )
+        i.r(left),
+        i.r(right)
+      ),
     }
   }
-}
+}