In the following:
julia> e = if false; end
julia> e
julia> f = match(r"x", “y”)
julia> f
julia> a = 
0-element Array{Any,1}
julia> e == a
false
julia> e == f
true
…What is the type of e and f which they are equal to?
In the following:
julia> e = if false; end
julia> e
julia> f = match(r"x", “y”)
julia> f
julia> a = 
0-element Array{Any,1}
julia> e == a
false
julia> e == f
true
…What is the type of e and f which they are equal to?
You can just ask the help system:
julia> f = match(r"x", "y")
help?> f
search: fd for fma fld fft full fld1 find filt fill fft! fdio
  No documentation found.
  f is of type Void.
  Summary
  ≡≡≡≡≡≡≡≡≡
  struct Void <: Any
help?> Void
search: Void @vectorize_2arg @vectorize_1arg versioninfo
  Void
  A type with no fields that is the type nothing.
help?> nothing
search: nothing
  nothing
  The singleton instance of type Void, used by convention
  when there is no value to return (as in a C void
  function). Can be converted to an empty Nullable value.
or just typeof if you just want to know the type.