Got from Mason Protter

specialize_vararg.jl

# by Mason Protter
using MacroTools: MacroTools, splitdef, combinedef, @capture
macro specialize_vararg(n::Int, fdef)
    d = splitdef(fdef)
    args = d[:args][end]
    @assert d[:args][end] isa Expr && d[:args][end].head == Symbol("...") 
    args_symbol = d[:args][end].args[]
    fdefs = Expr(:block)
    for i in 1:n-1
        di = deepcopy(d)
        pop!(di[:args])
        args = Tuple(gensym("arg$j") for j in 1:i)
        push!(di[:args], args...)
        pushfirst!(di[:body].args, :($args_symbol = $args))
        push!(fdefs.args, combinedef(di))
    end
    di = deepcopy(d)
    pop!(di[:args])
    args = tuple((gensym() for j in 1:n)..., :($(gensym("args"))...))
    push!(di[:args], args...)
    pushfirst!(di[:body].args, :($args_symbol = $(Expr(:tuple, args...))))
    push!(fdefs.args, combinedef(di))
    esc(fdefs)
end