[panglesd]

Very cool!

Does it replace identical expressions in the same scope? Like:

    let tau = 3.14 +. 3.14

becomes

    let pi = 3.14
    let tau = pi +. pi

?

EDIT: Or even crazier with function:

    let _ = (x + 1) + (y + 1)

becomes

    let plus_one a = a + 1
    let _ = (plus_one x) + (plus_one y)

(I ask this just out of curiosity. Even the "simpler" version is very impressive!)

[nukifw]

Nop, for the moment, we try to not "infer user usages"! But if you extract an expression with variable, there will be, obviously, not be repeated:

    let tau =
      let pi = 3.14 in 
      pi + pi

if we extract `pi + pi` it will lead (if you do not give any concrete name) to the following code:

    let fun_name1 pi = 
       pi + pi

    let tau = 
       let pi = 3.14 in 
       fun_name1 pi

[ethan_smith]

Most refactoring engines don't automatically replace all identical expressions by default since it can change semantics (especially with side effects), but they typically offer a separate "introduce and replace all occurrences" option that you can explicitly choose.

[greener_grass]

LLM generated variable names would be nice!