Higher ranked types is some form of higher order generics, but is not the same as higher kinded types (nested generics). A typical situation occurs, if we want to apply a length function to a collection of heterogenous types. I will present it here in Haskell syntax. The length function is itself …

Maybe you could translate this proposal to Julia for people who don’t understand the Haskell syntax? What problem would it solve in Julia?

@nalimilan , sorry for this. AFAIK, function types are at momentum a hot topic and I did not know the final syntax for it, but I will try it with the synatx from https://github.com/JuliaLang/julia/issues/210#issuecomment-35685282 Here is a suggestion: function length{T}(Array{T})::int function ap…

If I’m skimming and understanding that second link correctly, Julia already has far stronger support for higher rank and higher kindred types than Haskell: Haskell requires a language extension to use Rank-N types, while Julia is designed around dispatching with them. (I apologize in advance for any…

Interesting side note: Stephan Boyer, who wrote the second post linked, is the number 30 contributor to the Julia repo in terms of commits. Most of that was a web UI for Julia written in C++ from long before Jupyter/IJulia was a thing. If anyone has ever wondered why there’s a “ui” directory just fo…

Damn, julia is so f?ck?ng powerfull!!! The interesting point here is the type Type in julia. This is the higher order generic I’am searching for. The analogy of the type Type in julia is the similar for the class in java. Each data type in julia is an instance of Type: Int64 isa Type, Any isa Typ…

What are you trying to accomplish here?

I play around with higher order generics. One day, typed lambdas are supported, we can express to take parametric functions as argument, where the parametric parameter T has the meta order 2 (rank-2 type). Suppose we want to measure the length of different collection types T and we have a Pair p of…

No offense, but I think you need to stop thinking in Haskell here. In Julia, extreme polymorphism and genericity is the default, not something you need to jump through hoops to achieve. If you can explain in simple prose (without talking about types, ranks, higher orders or anything meta) what you w…

@StefanKarpinski What you presented above is subtype polymorphism, another way to sove the problem. The problem here, is not the len function , we can already express it (with intro of typed lambdas in future) with julia. The problem is to restrict the extreme polymorphism and genericity of ju…

Are there any plans to support higher order ranked types in julia?

Internals & Design

kristoffer.carlsson September 28, 2017, 11:59am 3

Perhaps you this is useful reading: Proposal for a first-class dispatch wrapper

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Are there any plans to support higher order ranked types in julia?

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