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| 2025-12-12 12:23:47 +0100 | <Enrico63> | It should be rank 2, I understand |
| 2025-12-12 12:23:33 +0100 | <mauke> | that still leaves (forall a. a) -> Int at rank 1 |
| 2025-12-12 12:23:18 +0100 | merijn | (~merijn@host-vr.cgnat-g.v4.dfn.nl) merijn |
| 2025-12-12 12:23:08 +0100 | <lucabtz> | yeah you were missing what Enrico63 added :P |
| 2025-12-12 12:22:53 +0100 | <mauke> | lucabtz: that one is mergeable |
| 2025-12-12 12:22:31 +0100 | <Enrico63> | *which are nested and cannot be merged with a previous one* |
| 2025-12-12 12:22:31 +0100 | <lucabtz> | mauke: it doesnt though, it says forall a. a -> (forall b. b -> a) is rank 1 |
| 2025-12-12 12:21:21 +0100 | <mauke> | the wiki page defines "rank" as the number of foralls in the type |
| 2025-12-12 12:20:59 +0100 | <Enrico63> | so that means `(forall a. a -> a) -> b` is rank 2, to my understanding. How is `(forall a. a) -> Int` any different in this respect? |
| 2025-12-12 12:20:26 +0100 | <Enrico63> | then in `(forall a. a -> a) -> b`, where there's an implicit `forall b.` in front of everyting, b is chosen by the caller, but a is chosen by the implementation |
| 2025-12-12 12:19:41 +0100 | <Enrico63> | and the caller "chooses" the `a` |
| 2025-12-12 12:19:13 +0100 | pabs3 | (~pabs3@user/pabs3) (Ping timeout: 246 seconds) |
| 2025-12-12 12:19:07 +0100 | <Enrico63> | `forall a. a -> a` (e.g. the type of id) is rank 1 |
| 2025-12-12 12:18:53 +0100 | <Enrico63> | Yeah, how's that? `Int -> Int` is rank 0, right? |
| 2025-12-12 12:18:40 +0100 | <mauke> | this doesn't feel right |
| 2025-12-12 12:18:26 +0100 | humasect | (~humasect@dyn-192-249-132-90.nexicom.net) (Remote host closed the connection) |
| 2025-12-12 12:18:21 +0100 | <mauke> | but then, according to that page (forall a. a) -> Int is rank 1 |
| 2025-12-12 12:18:04 +0100 | <Enrico63> | Umpf |
| 2025-12-12 12:17:20 +0100 | <mauke> | according to the wiki page, it's rank 2 |
| 2025-12-12 12:17:12 +0100 | <Enrico63> | mauke, that is rank 3? |
| 2025-12-12 12:16:59 +0100 | <mauke> | is that rank-2? |
| 2025-12-12 12:16:30 +0100 | <mauke> | forall b. ((forall a. a -> b) -> b) -> b |
| 2025-12-12 12:16:06 +0100 | <lucabtz> | i think rank N means it has rank N-1 as its arguments, the base case rank 0 being a monomorphic value/function |
| 2025-12-12 12:15:15 +0100 | trickard_ | (~trickard@cpe-83-98-47-163.wireline.com.au) |
| 2025-12-12 12:15:05 +0100 | <Enrico63> | I kind of get that. I suppose I want to do a quiz to make sure I have truly understood, rather than memoized some patterns |
| 2025-12-12 12:13:44 +0100 | <Enrico63> | Whereas rank 2 means that the implementation (i.e. the inner scope) chooses the type variable of the inner forall |
| 2025-12-12 12:12:39 +0100 | <haskellbridge> | <loonycyborg> With rank 1 all variables are set at outer scope and you won't be passing any polymorphic functions. |
| 2025-12-12 12:12:37 +0100 | <Enrico63> | loonycyborg, yeah, I'm also (halfway) there |
| 2025-12-12 12:12:31 +0100 | trickard | (~trickard@cpe-83-98-47-163.wireline.com.au) (Read error: Connection reset by peer) |
| 2025-12-12 12:12:08 +0100 | <haskellbridge> | <loonycyborg> I personally found the trick to understanding rank-n is that they're about polymorphic functions that can take other polymorphic functions. |
| 2025-12-12 12:12:00 +0100 | merijn | (~merijn@host-vr.cgnat-g.v4.dfn.nl) (Ping timeout: 245 seconds) |
| 2025-12-12 12:10:10 +0100 | <mauke> | (the answer is yes) |
| 2025-12-12 12:09:41 +0100 | <Enrico63> | Yeah, I don't quite get what's unclear to me, so I asked those previous questions to have something to hinge on |
| 2025-12-12 12:08:52 +0100 | <mauke> | well, it's what I would've used to answer your question :-) |
| 2025-12-12 12:07:52 +0100 | <Enrico63> | I come _from_ that page |
| 2025-12-12 12:07:01 +0100 | <mauke> | https://wiki.haskell.org/Rank-N_types |
| 2025-12-12 12:06:09 +0100 | <Enrico63> | It is rank 2, correct? |
| 2025-12-12 12:06:02 +0100 | <Enrico63> | Well, that's the same as `forall b. (forall a. a -> a) -> b` |
| 2025-12-12 12:05:37 +0100 | <Enrico63> | (Be damned the formatting, ahhah) |
| 2025-12-12 12:05:25 +0100 | <Enrico63> | Instead, if I have `(forall a. a -> a) -> b`, that's rank 2, right? |
| 2025-12-12 12:03:53 +0100 | <lucabtz> | yes rank 1 |
| 2025-12-12 12:02:08 +0100 | <Enrico63> | The id function has type `forall a. a -> a` which is rank 1, right? |
| 2025-12-12 12:02:07 +0100 | <Enrico63> | Hi, there. I'd like some clarification on rank-n types. |
| 2025-12-12 12:00:40 +0100 | Enrico63 | (~Enrico63@host-95-251-99-143.retail.telecomitalia.it) Enrico63 |
| 2025-12-12 11:52:30 +0100 | Katarushisu | (~Katarushi@finc-20-b2-v4wan-169598-cust1799.vm7.cable.virginm.net) (Ping timeout: 244 seconds) |
| 2025-12-12 11:44:50 +0100 | tromp | (~textual@2001:1c00:3487:1b00:dd4:56d:fd02:60e2) |
| 2025-12-12 11:42:56 +0100 | tromp | (~textual@2001:1c00:3487:1b00:dd4:56d:fd02:60e2) (Quit: My iMac has gone to sleep. ZZZzzz…) |
| 2025-12-12 11:38:15 +0100 | <gentauro> | related xD https://xkcd.com/2453/ |
| 2025-12-12 11:37:47 +0100 | merijn | (~merijn@host-vr.cgnat-g.v4.dfn.nl) merijn |
| 2025-12-12 11:27:55 +0100 | Tuplanolla | (~Tuplanoll@91-152-225-194.elisa-laajakaista.fi) Tuplanolla |