address minor review comments

src/algorithm/const_fold.rs

@@ -63,7 +63,7 @@ pub fn fold_const(op: &OpType, consts: &[(IncomingPort, Const)]) -> ConstFoldRes
                     }));
                 }
             }
-            None // could panic
+            panic!("This op always takes a Tuple input.");
         }
 
         LeafOp::Tag { tag, variants } => out_row([Const::new(
@@ -99,7 +99,8 @@ fn const_graph(consts: Vec<Const>, reg: &ExtensionRegistry) -> Hugr {
 /// [`SimpleReplacement`] replaces an operation with constants that result from
 /// evaluating it, the extension registry `reg` is used to validate the
 /// replacement HUGR. The vector of [`RemoveConstIgnore`] refer to the
-/// LoadConstant nodes that could be removed.
+/// LoadConstant nodes that could be removed - they are not automatically
+/// removed as they may be used by other operations.
 pub fn find_consts<'a, 'r: 'a>(
     hugr: &'a impl HugrView,
     candidate_nodes: impl IntoIterator<Item = Node> + 'a,

src/extension/op_def.rs

@@ -309,6 +309,7 @@ pub struct OpDef {
     #[serde(flatten)]
     lower_funcs: Vec<LowerFunc>,
 
+    /// Operations can optionally implement [`ConstFold`] to implement constant folding.
     #[serde(skip)]
     constant_folder: Box<dyn ConstFold>,
 }

src/std_extensions/arithmetic/float_ops.rs

@@ -14,7 +14,7 @@ use crate::{
     Extension,
 };
 use lazy_static::lazy_static;
-mod fold;
+mod const_fold;
 /// The extension identifier.
 pub const EXTENSION_ID: ExtensionId = ExtensionId::new_unchecked("arithmetic.float");
 
@@ -84,7 +84,7 @@ impl MakeOpDef for FloatOps {
     }
 
     fn post_opdef(&self, def: &mut OpDef) {
-        fold::set_fold(self, def)
+        const_fold::set_fold(self, def)
     }
 }