A.vec_size

You're seeing just the macro vec_size, go back to A module for more information.
Link to this macro

vec_size(vector)

View Source (macro)

Returns the size of a vector.

It is implemented as a macro so that it can be used in guards.

When used outside of a guard, it will just be replaced by a call to A.Vector.size/1.

When used in guards, it will fail if called on something else than an A.Vector. It is recommended to verify the type first.

Runs in constant time.

Examples

iex> import A
iex> match?(v when vec_size(v) > 20, A.Vector.new(1..10))
false
iex> match?(v when vec_size(v) < 5, A.Vector.new([1, 2, 3]))
true
iex> vec_size(A.Vector.new([1, 2, 3]))
3