This is an example of "ugly" Forth code. It's ok here to make the code as short as possible.

In reality I would write (educational) Forth code this way. The texts in parentheses are comments.

  ( compute Hypotenuse sqrt[a²+b²] )
  : hypo       ( a  b   )
    swap       ( b  a   )
    dup *      ( b  a²  )
    swap       ( a² b   )
    dup *      ( a² b²  )
    +          ( a²+b²  )
    sqrt       ( result )
  ;

  ( Application:  1.2 3.4 hypo )