Module helpers 

Functions

count_free_occurrences

Count how many times var appears free in expr.

count_nodes

Count total nodes in an expression tree.

expr_depth

Compute the depth (height) of an expression tree.

is_constant_binding

Returns true if expr is a constant literal (Constant(_)).

is_simple_binding

Returns true if expr is a “simple” binding worth inlining regardless of use count: either a constant or a variable alias.

is_var_binding

Returns true if expr is a zero-argument predicate (variable alias).