`Vector{Function}` behaves strangely when length is one

General Usage
,
1 
julia> f(x)=x+1
f (generic function with 1 method)

julia> isa(f, Function)
true

julia> typeof([f])
Vector{typeof(f)} (alias for Array{typeof(f), 1})

julia> f1(x)=x+1
f1 (generic function with 1 method)

julia> typeof([f,f1])
Vector{Function} (alias for Array{Function, 1})
2

f has type typeof(f) and a single-element vector chooses the most specific eltype typeof(f). You can use Function[f] or Any[f] to let more callables in.

3 Likes
3

Does this clear things up?

julia> promote_type(typeof(sin))
typeof(sin) (singleton type of function sin, subtype of Function)

julia> promote_type(typeof(sin), typeof(cos))
Function
3 Likes
4

Yes, thank you.

1 Like