mixfix notation (mix in- post- prefix notations in same way)

infix	mixfix
(5x + 2) - 2	(x5 2 +) 2 -
4 * (5 * (8 / 5))	* 4 (5 (8 5 /) *)
5y + 2x	y5 + x2
sinθ + cosθ	sinθ cosθ + (or θsin θcos +)
5tanβ + 2sinθ	5tanβ 2sinθ + (βtan5 θsin2 +)
√10	√10 (or 10√)
2√10	√10 2 (or 10√2)

mixfix notation can be a bit better for expression parsers