All function arguments should receive a new placeholder

[jiegillet]

All function arguments should receive a new placeholder, since local names take over global names.

Example input

def add(a, b), do: a + b
def combine(add, mult), do: fn x, y, z -> add(x, mult(y, z)) end

Desired result

  def(PLACEHOLDER_1(PLACEHOLDER_2, PLACEHOLDER_3)) do
    PLACEHOLDER_2 + PLACEHOLDER_3
  end
  def(PLACEHOLDER_4(PLACEHOLDER_5, PLACEHOLDER_6)) do
    fn PLACEHOLDER_7, PLACEHOLDER_8, PLACEHOLDER_9 -> PLACEHOLDER_5(PLACEHOLDER_7, PLACEHOLDER_6(PLACEHOLDER_8, PLACEHOLDER_9)) end
  end

Current result

  def(PLACEHOLDER_1(PLACEHOLDER_2, PLACEHOLDER_3)) do
    PLACEHOLDER_2 + PLACEHOLDER_3
  end
  def(PLACEHOLDER_4(PLACEHOLDER_1, PLACEHOLDER_5)) do
    fn PLACEHOLDER_6, PLACEHOLDER_7, PLACEHOLDER_8 -> PLACEHOLDER_1(PLACEHOLDER_6, PLACEHOLDER_5(PLACEHOLDER_7, PLACEHOLDER_8)) end
  end

Note that the argument add in combine/PLACEHOLDER_4 has been replaced by PLACEHOLDER_1 as assigned in add/PLACEHOLDER_1 but has no connection to it and should be called PLACEHOLDER_5 instead.

[jiegillet]

I stand corrected, I read the documentation a bit more closely and it mentions (at the end)

It is important to note that all identical names must be replaced with the same placeholder, irrespective of scope.

I suppose it is important so we can comment on that very thing, for example: "you shouldn't shadow an existing variable name".