30 September 2016

valFORTH has a built-in definition for INITIALIZE, a 1-based PICK, limited input line length, and no semantics for instantiating an infinite DO loop.

32767 CONSTANT MAXINT
: CELLS  2* ;
: #PRIME@  2 + CELLS + ;
: #PRIME  >R DUP R> #PRIME@ @ ;
: #PRIMES  DUP 1 CELLS + @ ;
: #PRIMES++  #PRIMES 1+ OVER 1 CELLS + ! ;
: MAXPRIMES  DUP @ ;
: NOTPRIME  DROP 0 ;
: DIVIDES?  MOD 0= ;
: PINIT  DUP >R HERE DUP R> 2 + CELLS ALLOT ROT SWAP !
0 OVER 1 CELLS + ! ;
: ISPRIME!  DUP . CR OVER #PRIMES #PRIME@ ! #PRIMES++ ;
: ISPRIME?  OVER #PRIMES 0 DO I #PRIME 3 PICK SWAP DIVIDES?
IF NOTPRIME LEAVE THEN LOOP ;
: PRIMES  PINIT CR 2 ISPRIME!
MAXINT 3 DO I ISPRIME? IF ISPRIME! ELSE DROP THEN
MAXPRIMES >R #PRIMES R> = IF LEAVE THEN LOOP ;