4 ms·

Since other array languages are being brought up already, here are two things K does that you won't find anywhere else in the APL family as far as I know: - Di

Since other array languages are being brought up already, here are two things K does that you won't find anywhere else in the APL family as far as I know: - Dicts (same as hashmaps, associative arrays, etc.) are a native datatype, with `ab`cd!0 1 indicating a dict mapping symbols `ab and `cd to 0 and 1, for example. In K4 and later (ngn/k implements K6), array primitives work on them to do all sorts of fancy things. For example prefix &, "where", returns the indices of any 1s in an array. If given a dict, it gives you the keys corresponding to 1s. - Partial application. If you have a function f of two arguments, f[;x] binds the second argument x to f, but leaves the first one unbound. So f[;x][y] is f[x;y]. But that's not nearly all: arrays, dicts, and functions are unified, so if fs is a list of one-argument functions, then fs[;x] applies each function to x. This is because fs[;x][i] is fs[i;x] or fs[i][x]! ngn/k is the best implementation to use now in my opinion. It's short on documentation, but the K Wiki is a new and very nice resource for K. Maybe start with the list of all primitives at https://k.miraheze.org/wiki/Primitives https://k.miraheze.org/wiki/Primitives .

moonchild 4y ago
> ngn/k is the best implementation to use now in my opinion why?
- memorable 4y ago
  The biggest win for me to use ngn/k is the built-in documentation. K is primarily taught through refcards, and most K refcards that you find in implementations are quite compact, like this: https://kparc.com/k.txt https://kparc.com/k.txt While refcards like this are perfectly fine, they can confuse beginners at specific parts in the text. This is where ngn/k shines. It has a robust documentation system, containing several help commands for multiple subjects (types, verbs, adverbs, etc.). They also contain examples, have clear separation between subjects, and are way less ambiguous.
bakul 4y ago
> So f[;x][y] is f[x;y]. f[y;x]
- avmich 4y ago
  Yes. And J has & to bind left or right argument to a dyad making it a monad - e.g. -&5 allows (-&5) 11 which evaluates to 6, while (5&-) 11 evaluates to _6 .
vanderZwan 4y ago
I was going to say "wouldn't BQN have dicts since it's trying to be a more accessible, modern, from-the-ground-up designed APL and dictionaries are pretty damn useful?" but then I noticed your username so I guess that answers that. So now I'm curious: why didn't you include some version these features in BQN? They seem pretty nice to have! EDIT: will you ever write a "let's learn BQN by figuring out how the self-hosted compiler is implemented!" article? I doubt I'll use BQN soon but I find it a fascinating, extremely interesting language, and I'm just super-curious how you implemented the self-hosting compiler.
- mlochbaum 4y ago
  Languages with multidimensional arrays (APL, BQN, J, but not K) have trouble with dicts because an index into an array is a list of numbers, and an index into a dict is an arbitrary value. Many primitives, and especially selection, are designed around lists of numbers and don't transfer to dicts. In K, where the index into a list is one number, there's still a requirement that the keys in a dict all have the same level of nesting, but this isn't bad in practice. BQN will eventually have hashmaps implemented as in a more mainstream/conventional way, as objects. There's a model at https://github.com/mlochbaum/bqn-libs/blob/master/hashmap.bqn https://github.com/mlochbaum/bqn-libs/blob/master/hashmap.bq... . I don't think studying the compiler is a very good way to learn BQN, but I would like to write up parts of it (limited by time and motivation of course). I did some chat sessions on this sort of compilation during early development; see the links at the bottom of https://mlochbaum.github.io/BQN/implementation/ https://mlochbaum.github.io/BQN/implementation/ .

moonchild 4y ago

> ngn/k is the best implementation to use now in my opinion why?

memorable 4y ago
The biggest win for me to use ngn/k is the built-in documentation. K is primarily taught through refcards, and most K refcards that you find in implementations are quite compact, like this: https://kparc.com/k.txt https://kparc.com/k.txt While refcards like this are perfectly fine, they can confuse beginners at specific parts in the text. This is where ngn/k shines. It has a robust documentation system, containing several help commands for multiple subjects (types, verbs, adverbs, etc.). They also contain examples, have clear separation between subjects, and are way less ambiguous.

bakul 4y ago

> So f[;x][y] is f[x;y]. f[y;x]

avmich 4y ago
Yes. And J has & to bind left or right argument to a dyad making it a monad - e.g. -&5 allows (-&5) 11 which evaluates to 6, while (5&-) 11 evaluates to _6 .

vanderZwan 4y ago

I was going to say "wouldn't BQN have dicts since it's trying to be a more accessible, modern, from-the-ground-up designed APL and dictionaries are pretty damn useful?" but then I noticed your username so I guess that answers that. So now I'm curious: why didn't you include some version these features in BQN? They seem pretty nice to have! EDIT: will you ever write a "let's learn BQN by figuring out how the self-hosted compiler is implemented!" article? I doubt I'll use BQN soon but I find it a fascinating, extremely interesting language, and I'm just super-curious how you implemented the self-hosting compiler.

mlochbaum 4y ago
Languages with multidimensional arrays (APL, BQN, J, but not K) have trouble with dicts because an index into an array is a list of numbers, and an index into a dict is an arbitrary value. Many primitives, and especially selection, are designed around lists of numbers and don't transfer to dicts. In K, where the index into a list is one number, there's still a requirement that the keys in a dict all have the same level of nesting, but this isn't bad in practice. BQN will eventually have hashmaps implemented as in a more mainstream/conventional way, as objects. There's a model at https://github.com/mlochbaum/bqn-libs/blob/master/hashmap.bqn https://github.com/mlochbaum/bqn-libs/blob/master/hashmap.bq... . I don't think studying the compiler is a very good way to learn BQN, but I would like to write up parts of it (limited by time and motivation of course). I did some chat sessions on this sort of compilation during early development; see the links at the bottom of https://mlochbaum.github.io/BQN/implementation/ https://mlochbaum.github.io/BQN/implementation/ .