bug fixes and performance improvements

src/rule/update_first_seq.rs

@@ -0,0 +1,36 @@
+use std::rc::Rc;
+
+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>(input: Rc<Vec<Expr>>, pred: &mut F) -> Option<Rc<Vec<Expr>>>
+where F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>> {
+  if let o@Some(_) = pred(input.clone()) {return o} 
+  replace_first(input.as_ref(), |ex| expr(ex, pred))
+    .map(|i| Rc::new(i.collect()))
+}
+
+pub fn expr<F>(input: &Expr, pred: &mut F) -> Option<Expr>
+where F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>> {
+  if let Some(value) = clause(&input.value, pred) {
+    Some(Expr{ value, location: input.location.clone() })
+  } else {None}
+}
+
+pub fn clause<F>(c: &Clause, pred: &mut F) -> Option<Clause>
+where F: FnMut(Rc<Vec<Expr>>) -> Option<Rc<Vec<Expr>>> {
+  match c {
+    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}
+    }
+    Clause::S(c, body) => Some(Clause::S(*c, exprv(body.clone(), pred)?)),
+  }
+}