Insert muladds in `a1*a1 + a2*b2 + ...` expressions

muladd_macro.jl

module Muladd

macro muladd(ex)
  @assert ex.head == :call
  @assert ex.args != [:+]
  @assert ex.args[1] == :+
  esc(_muladd_meta(ex))
end

function _muladd_meta(ex)
  if length(ex.args) == 2
    return ex.args[2]
  else
    a, b = ex.args[2].args[2:end]
    rest = _muladd_meta(Expr(ex.head, :+, ex.args[3:end]...))
    return :($(Base.muladd)($a, $b, $rest))
  end
end

end

Version with informative names/functions, error handling, tests and all that: https://gist.github.com/fcard/12a49827cc26a197d4d1e75481216176