Fix reduce builtin

[erik-adelbert]

#2880 introduced a buggy reduce builtin which operates on the given list from right to left. So this:

reduce(lambda x, y: ''.join((x, y)), ["a", "b", "c", "d", "e"])

incorrectly returns "edcba" instead of "abcde".

The proposed patches hopefully solve this bug.

[Tatskaari]

Thanks! This definitely wasn't intentional. Looks like the Python one is left associative which is inline with this change.

[Tatskaari]

This was copied from here:
https://docs.python.org/3/library/functools.html#functools.reduce

Looks like you've changed the arg name as well which makes it inconsistent with Python if I understand correctly. Should we switch this back?

[erik-adelbert]

right now it is in line with its neighbours in please code but yes we can make it in line with python instead

[erik-adelbert]

please/docs/lexicon.html

Lines 177 to 181 in 8d9ffe8

	<code class="code"
	><span class="fn-name">map</span><span class="fn-p">(</span
	><span class="fn-arg">mapper</span>, <span class="fn-arg">seq</span
	><span class="fn-p">)</span></code
	>