Specify type of function

[linuslagerhjelm]

Let’s say that I want to write a higher order function (a function that accepts another function) I know I can accept it like:

fun(f::Function, args...) = ...

What I want to know if it is possible to be more specific about the type of f, if I expect the function to have a certain format, for example a predicate function would need to accept two values of a special type and return a Bool. Something like:

fun(f::(x1::T, x2::T)::Bool, Vector{T}) where T = ...

If this is not currently possible I think it would be a nice feature request.

[jonathanBieler]

You can check this comment and the rest of the thread:

Enforcing function signatures by both argument & return types

It’s becoming a bit complicated but I think this works: Now you can provide the signature you want to the constructor and it look through the function’s methods to find a match (returns an error otherwise) f(z,x::Int,y::Int) = x+z f(x::Int,y::Float64) = x+y f(x::Int) = x f() = 2 julia> tf1 = TypedFunction(f, (Int,Float64),(Float64)) f: Tuple{Int64,Float64} → Float64 You can use dispatch to put constrains on input/output types: g(f::TypedFunction{T,I,O}) where {T,I<:Tuple{Number,Float64},O<:…

[linuslagerhjelm]

Ah nice! Thank you!