Wait, now I need to know why.
* some time later *
I went to check why the hell this happened. It looks like the pair ("(,)
") is defined as an instance of Foldable
, for some reason, which is the class used by functions like foldl()
and foldr()
. Meanwhile, triples and other tuples of higher order (such as triples, quadruples, ...) are not instances of Foldable
.
The weirdest part is that, if you try to use a pair as a Foldable
, you only get the second value, for some reason... Here is an example.
ghci> foldl (\acc x -> x:acc) [] (1,2)
[2]
This makes it so that the returned length is 1.
OP, I don't think you've correctly linked to the post (when I visit the linked webpage, the browser tries to download an ActivityPub activity instead of showing the post in the Mastodon web UI). Please replace the link with this one.