Okay, so I’ve been messing around with Idris lately, and I stumbled upon this thing called “idris-k”. It sounded kinda cool, like some advanced Idris feature I hadn’t explored yet. So, I decided to dig in and see what it’s all about. Here’s how it went down:
First things first, I fired up my trusty terminal and tried to just, you know, see if Idris knew anything about it. I typed in some commands, hoping something would magically pop up. Nothing. Zilch. Nada. Okay, so maybe it wasn’t a built-in command or anything.
Next step, I hit the web. I started Googling “idris-k”, “idris dependent types”, “idris kind polymorphism” – you name it, I searched it. I found some scattered mentions in research papers and forum posts, but nothing super concrete that screamed, “This is idris-k, and here’s how you use it!” It felt like chasing a ghost.
I eventually pieced together that “idris-k” isn’t really a thing you install or a specific library. It’s more like a concept. It’s about using kinds in Idris in a more powerful way. Think of it like… leveling up your type-fu. It’s all about making your types even more descriptive and letting the compiler catch even more errors for you.
The main idea, as far as I could tell, is to use kinds to express relationships between types that go beyond the usual “this type is a set of values” thing. Instead of just saying `x : Nat`, you might say something that indicates how that `Nat` is used, or what role it plays in a larger structure. This is done by creating custom kinds with data declarations. It makes it possible to enforce constraints at the kind level.
So, I started experimenting. I created some simple data types and then defined custom kinds to represent different ways those types could be used. It was tricky at first. I kept getting weird compiler errors, mostly because I was still wrapping my head around how kinds really worked. It’s like, you think you understand types, and then kinds come along and blow your mind all over again.
Here’s a tiny, somewhat silly example of what I played with, just to give you a flavor:
data MyKind = Thing1 Thing2
data MyType : MyKind -> Type where
MkThing1 : MyType Thing1
MkThing2 : MyType Thing2
-- This would be an error, because the kinds don't match
-- badThing : MyType Thing2
-- badThing = MkThing1
See, I made a custom kind `MyKind`, and then `MyType` is parameterized by that kind. This lets me say that `MkThing1` must have the kind `Thing1`, and `MkThing2` must have the kind `Thing2`. The commented-out `badThing` shows what would happen if I tried to mix them up – the compiler would yell at me.
After a lot of trial and error, and a lot of staring at compiler messages, I started to get the hang of it. I managed to write some small programs where the kinds actually helped me catch some subtle bugs. It felt good! Like I was finally starting to unlock the real power of Idris.
Honestly, “idris-k” isn’t something you just pick up in an afternoon. It takes time, practice, and a willingness to bang your head against the wall occasionally. But it’s also incredibly rewarding. It’s like learning a new language – a language for talking about types in a much richer and more precise way. I still have a ton to learn, but I’m definitely hooked. I am going to practice it more.