Preparation for sharing

- rustfmt
- clippy
- comments
- README

src/rule/update_first_seq.rs

@@ -1,39 +1,42 @@
 use std::rc::Rc;
 
+use crate::ast::{Clause, Expr};
 use crate::utils::replace_first;
-use crate::ast::{Expr, Clause};
 
 /// Traverse the tree, calling pred on every sibling list until it returns
 /// some vec then replace the sibling list with that vec and return true
 /// return false if pred never returned some
-pub fn exprv<
-  F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
->(input: Rc<Vec<Expr>>, pred: &mut F) -> Option<Rc<Vec<Expr>>> {
-  if let o@Some(_) = pred(input.clone()) {return o} 
+pub fn exprv<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
+  input: Rc<Vec<Expr>>,
+  pred: &mut F,
+) -> Option<Rc<Vec<Expr>>> {
+  if let Some(v) = pred(input.clone()) {
+    return Some(v);
+  }
   replace_first(input.as_ref(), |ex| expr(ex, pred))
     .map(|i| Rc::new(i.collect()))
 }
 
-pub fn expr<
-  F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
->(input: &Expr, pred: &mut F) -> Option<Expr> {
-  if let Some(value) = clause(&input.value, pred) {
-    Some(Expr{ value, location: input.location.clone() })
-  } else {None}
+pub fn expr<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
+  input: &Expr,
+  pred: &mut F,
+) -> Option<Expr> {
+  clause(&input.value, pred)
+    .map(|value| Expr { value, location: input.location.clone() })
 }
 
-pub fn clause<
-  F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>
->(c: &Clause, pred: &mut F) -> Option<Clause> {
+pub fn clause<F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>>>(
+  c: &Clause,
+  pred: &mut F,
+) -> Option<Clause> {
   match c {
-    Clause::P(_) | Clause::Placeh {..} | Clause::Name {..} => None,
-    Clause::Lambda(arg, body) => {
+    Clause::P(_) | Clause::Placeh { .. } | Clause::Name { .. } => None,
+    Clause::Lambda(arg, body) =>
       if let Some(arg) = expr(arg.as_ref(), pred) {
         Some(Clause::Lambda(Rc::new(arg), body.clone()))
-      } else if let Some(body) = exprv(body.clone(), pred) {
-        Some(Clause::Lambda(arg.clone(), body))
-      } else {None}
-    }
+      } else {
+        exprv(body.clone(), pred).map(|body| Clause::Lambda(arg.clone(), body))
+      },
     Clause::S(c, body) => Some(Clause::S(*c, exprv(body.clone(), pred)?)),
   }
-}
+}