Conversion: Algebraic - Polish - Reverse Polish - LISP ?

[Thomas Klemm]

It turned out to be easier than I expected.
Save the following program in →PN:

Code:

« OBJ→
  IF OVER
  THEN → n f
    « 1 n
      FOR i
        IF DUP TYPE 9 SAME
        THEN →PN
        END 1 →LIST n ROLLD
      NEXT
      IF n 1 >
      THEN 2 n
        START +
        NEXT
      END f SWAP +
    »
  ELSE 1 →LIST SWAP DROP
  END
»

Example

'x*(1+x*(1-x))*SIN(x)'
→PN

{ * { * x { + 1 { * x { - 1 x } } } } { SIN x } }