1010
JavaScript
(lemmy.ml)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 04 Jun 2025
1010 points (98.6% liked)
Programmer Humor
23899 readers
1587 users here now
Welcome to Programmer Humor!
This is a place where you can post jokes, memes, humor, etc. related to programming!
For sharing awful code theres also Programming Horror.
Rules
- Keep content in english
- No advertisements
- Posts must be related to programming or programmer topics
founded 2 years ago
MODERATORS
This is my favorite language: GHC Haskell
GHC Haskell:
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 ofFoldable, for some reason, which is the class used by functions likefoldl()andfoldr(). Meanwhile, triples and other tuples of higher order (such as triples, quadruples, ...) are not instances ofFoldable.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.This makes it so that the returned length is 1.
Oddly enough, in Haskell (as defined by the report), length is monomorphic, so it just doesn't work on tuples (type error).
Due to the way kinds (types of types) work in Haskell, Foldable instances can only operate over (i.e. length only counts) elements of the last/final type argument. So, for (,) it only counts the second part, which is always there exactly once. If you provided a Foldable for (,,,) it would also have length of 1.