Function bare_fn_value_type 

pub fn bare_fn_value_type(
    expr: &Expr,
    v: &[Variable],
    ctx: Ctx,
    state: &State<'_>,
) -> Option<DataType>

The type of expr where it is a bare name that means a declared function and the position holds the function rather than calls it.

None for anything else, which leaves a closure bound to a name and a call through a name the compiler can settle lowering to the jump they were.