Hey guys, I just ran into a problem where I had a runtime issue where some code tried to iterate over a non-iterable type and then I ran into the definition in the standard library. struct Enumerate{I} itr::I end enumerate(iter) = Enumerate(iter) function iterate(e::Enumerate, state=(1,)) …

[image] marvinvanaalst: Having incorrectly typed functions in the standard library does seem like a major issue to me though, especially when it comes to people who may want to proof the correctness of their programs. I think that the term “incorrectly typed function” is not very useful in Ju…

[image] marvinvanaalst: so the only solution that really fits that description is the hasmethod example. But if that this only works at runtime it seems a major drawback for tooling, as I would like to do this statically. Tricks.jl has a static_hasmethod which is compile-time. Composed with W…

[image] marvinvanaalst: Having incorrectly typed functions in the standard library it’s not incorrectly typed, it’s not typed at all. enumerate(iter) takes Anything. But consider this is like saying for x in BLAH shouldn’t call iterate(BLAH) because Julia’s base can’t prove BLAH is iterable.…

Afaik the reason you can do julia> struct Foo end julia> enumerate(Foo()) enumerate(Foo()) isn’t based on principle since it doesn’t have much (any?) benefit. It’s more just due to the technical reason that Julia hasn’t figured out its trait system yet. I think Julia’s sparse use of type signatu…

[image] jzr: represent higher order functions in the type system IIRC Julia never intended to have typed function if you’re thinking about OCaml or a like, not just “currently”. Julia’s typing system is built for multi-dispatch, not for proof etc. in the realm of type theory. It doesn’t mean …

For future readers: some folks have been looking for (and working on) stuff like that [image] Higher-order function argument types General Usage You may find these related discussions useful. They have pointers to discussions in issues, and other discussions on this forum…

Wow, thanks for all the input and the lively discussion! [image] tisztamo: I think that the term “incorrectly typed function” is not very useful in Julia. AFAIK it is considered best practice to use function signatures only for dispatch , and not for safety or other motivations of restricting. …

Static analysis is newly available with JET.jl . But I don’t think that’s the whole story. I want to have a well typed system (with clear interfaces), not just static analysis. I also don’t think include or multiple dispatch harms much – or is even really related. Nor is the dynamism at fault.

[image] marvinvanaalst: But it seems like it could be extended. Just in case it’s not obvious, you can put any expressions in that where clause, so you can already do where {static_hasmethod(a,...) && static_hasmethod(b,...)} etc… With some helper functions, willing to bet it can be done pret…

A lot of very interesting topics came out here, thank you all for the links and thoughts! Interestingly, I start to have the feeling that our vocabulary differs so much that it is hard to understand each other. e.g. This great article talks about static typing, which is roughly using function sign…

Structural subtyping

New to Julia

jzr July 10, 2021, 10:57pm 11

For future readers: some folks have been looking for (and working on) stuff like that

2 Likes

Topic		Replies	Views
What interface bugs have you ran into in the ecosystem? General Usage question	35	1729	January 31, 2024
Proposal: Adding Optional Static Interface/Traits Checking to Julia Internals & Design question	32	1334	February 17, 2025
Comparison of Julia with statically typed languages New to Julia question	10	2366	June 9, 2024
How can we maintain easy generics in the face of demand for a “safe” language? Internals & Design	26	1489	February 7, 2024
Why did Julia choose nominal typing over structural typing/traits? Internals & Design question , design , traits , interface	29	1963	November 16, 2024

Structural subtyping

Related topics