Hi ! I’ve encountered something curious, and here is a minimal example :slight_smile: function f(x::UInt,y::UInt)::UInt x + y end And now i want to do f(2,2) but julia says this to me : julia> f(2,2) ERROR: MethodError: no method matching f(::Int64, ::Int64) Stacktrace: [1] top-level scope…

[image] lhp22: but UInt8 <: UInt is true, isn’t it ? Try it out: julia> UInt8 <: UInt false Maybe you are looking for Unsigned instead? That’s the supertype of all unsigned integers: julia> UInt8 <: Unsigned true Now even if you define f(x::Unsigned, y::Unsigned) this will still not allow…

As you’ve noticed, 2 is cast to Int, which on a 64-bit system is Int64. 0x2 is UInt8. This is NOT <: UInt, though, since UInt is UInt64 on 64-bit systems. Just call it with UInt(...): f(UInt(2), UInt(2)), or coerce inside the function: julia> function f(x::Integer, y::Integer) ux = UInt(…

Ok. 1/ I’ve a problem with the number system types. I should read the doc again. 2/ Thanks for your answers to you both ! I’ve already thought to the first, but it seemed to me strange. The second is more julia-like. Thanks for your quick answers !

[image] lhp22: For a function, I need just positive numbers, no I want to force this by the typing. Why do you want to enforce this with the type? Types in the function signature are great for multiple dispatch, but I think a more common pattern for argument checking is something like functi…

Note that the generic error function isn’t a good fit here since it obscures the actual error in a generic message. Contrast that with the sqrt function, which properly throws a DomainError: julia> using Test julia> @test_throws DomainError sqrt(-1) Test Passed Thrown: DomainError which is …

Because I have a complex type system ? It should be unnice if I couldn’t use it for easing my code :slight_smile:

Having a complex type system does not mean you have to or should use it for everything. In fact, using it to restrict user input is almost always bad. The user will have a MUCH better time understanding the error message from sqrt(-1) than from your function.

[image] StefanKarpinski: You can write Julia code without types just like you would Python, R or Matlab. [!Warning Pendantic!] Yes but isn’t there a caveat that if you leave out types from structs and data objects altogether it will lead to a degradation in performance where the compiler star…

Sure, but no worse than those languages.

Yes, but Julia is better. Having a type system in a dynamic language that creates efficient code is mind-blowing :exploding_head:. You couldn’t write something like this in any other language; Julia parser and writer for the IDX file format used by e.g. the MNIST dataset · GitHub just explicit and s…

[SOLVED] UInt is not Int!

New to Julia

StefanKarpinski May 23, 2020, 9:28pm 9

If you don’t want to, don’t put types on your function signatures. It’s not required or even helpful for performance. You can write Julia code without types just like you would Python, R or Matlab.

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[SOLVED] UInt is not Int!

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