Been playing with gforth

[GreyGeek]

Back in the very early 1980s I used AceForth on a Tandy Xenix to write an autoparts hardware application for a client.

A couple weeks ago I installed gforth and began playing with it. I wrote a program that computes the number of primes from 0 to some given number.
In a Konsole running gforth I computed all the primes between 0 and 10,000,000. It took 23 seconds.

: PRIMES ( n - )
  2 SWAP 2 . 3 . 5
  DO DUP DUP * i < 
     IF 1+ 
     THEN 
     1 OVER 1+ 3
     DO     J I MOD 0=
            IF 1- LEAVE 
            THEN 
            2 
     +LOOP
     IF I . 
     THEN 
     2 
  +LOOP
  DROP ;