Hi there, Julia’s dispatch is something we all love, but I can’t figure out the syntax for the case of creating the signature of a function which takes another function as an arg. _ _ _ _(_)_ | Documentation: https://docs.julialang.org (_) | (_) (_) | _ _ …

[image] Alex_Ellison: if I try… julia> typeof(h) typeof(h) … I get output which to me seems unhelpful. Did you try to annotate _f with this? It actually works! julia> function h(_f::typeof(f), x::Number) return g(_f(x)) end h (generic function with 1 method) julia> h(f, …

Alternatively if you just want your function h to call any function passed, not just f (which is presumably the case since otherwise you wouldn’t have it as an argument and just fixed in the code) you can use the ::Function annotation. (I don’t know Haskell so I can’t tell if that’s what you are try…

[image] Alex_Ellison: a->a I’m pretty sure in Haskell this means something like “a function with one argument, and one return value, which both have the same type”. Is that right? I don’t think you can do that in Julia, at least partially because functions can’t be described in that way. Cons…

A couple of relevant prior discussions, in case you’re interested: Ability to define function templates - #7 by jeff.bezanson Function Parameter Speculation #17168 - #7 by jameson Proposal for a first-class dispatch wrapper

How to type annotate functions which take functions as args

New to Julia

rdeits August 28, 2018, 4:15am 5

A couple of relevant prior discussions, in case you’re interested:

Ability to define function templates - #7 by jeff.bezanson
Function Parameter Speculation #17168 - #7 by jameson
Proposal for a first-class dispatch wrapper

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How to type annotate functions which take functions as args

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