IF
Syntax IF expression [then-instructions] 
IF expression [then-instructions] [else-instructions] 
IF expression THEN instructions 
IF expression THEN instructions ELSE instructions 
 
Explanation IF runs the first set of instructions if the result of the expression is TRUE. If the expression is FALSE, the second set of instructions, if present, is run.

See also IFFALSE and IFTRUE.
Examples TO TRY :NUMBER
     IF :NUMBER >100 THEN PR [THE NUMBER IS TOO BIG] STOP 
     FD :NUMBER 
     LT 90
END
TRY defined
TRY 105 
THE NUMBER IS TOO BIG 
TO AGAIN?
     PRINT "|Do you want to play again?| 
     IF RQ = "Y [GAME] [PRINT "|Thanks for playing!| TOPLEVEL]
END
AGAIN? defined
AGAIN? 
Do you want to play again?
N
Thanks for playing! 

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