get all concrete subtypes of a Julia abstract type

subtypes.jl

julia> function _subtypes(type::Type)
          out = Any[]
          _subtypes!(out, type)
      end
_subtypes (generic function with 1 method)



julia> function _subtypes!(out, type::Type)
          if !isabstracttype(type)
              push!(out, type)
          else
              foreach(T->_subtypes!(out, T), subtypes(type))
          end
          out
      end

_subtypes! (generic function with 1 method)



julia> _subtypes(Number)

19-element Array{Any,1}:

Complex  

BigFloat  

Float16  

Float32  

Float64  

Irrational

Bool      

BigInt    

Int128    

Int16    

Int32    

Int64    

Int8      

UInt128  

UInt16    

UInt32    

UInt64    

UInt8    

Rational