┬Y FAR THE MOST READ (AND BEST) INSTRUCTIONAL BOOK ON ╞ORTH IS ╙╘┴╥╘╔╬╟ ╞╧╥╘╚, BY ╠EO ┬RODIE. ╔T IS VERY CLEAR, AMUSING, AND COVERS THE TERRITORY. ╒NFORTUNATELY, SINCE ╙TARTING ╞ORTH WAS WRITTEN, ╞ORTH ITSELF HAS UNDERGONE CONSIDERABLE EVOLUTION, SO NOT EVERYTHING IN ╙TARTING ╞ORTH IS APPLICABLE TODAY. ┴DDITIONALLY, ╙TARTING ╞ORTH IS BASED ON A PARTICULAR DIALECT OF ╞ORTH (╨╧╠┘-╞╧╥╘╚), WHICH IS A ╞ORTH IMPLEMENTATION BY ╞ORTH ╔NC., THE COMPANY ═R. ┬RODIE WORKED FOR WHEN HE WROTE HIS EXCELLENT BOOK. ┴S A RESULT, EVEN FOR THE TIME IT WAS WRITTEN, CERTAIN PASSAGES AND EXAMPLES WOULD NOT WORK ON ANYTHING BUT A ╞ORTH ╔NC. SYSTEM. ( .╙ IS A CLASSIC EXAMPLE OF THIS, BUT THERE ARE OTHERS. )
┬LAZIN' ╞ORTH IS WRITTEN TO SUPPORT THE ╞ORTH-83 STANDARD. ╘HIS IS THE MOST RECENT AVAILABLE STANDARD, AND THE ONE WHICH IN MY OPINION, AND FROM ALL ╔ CAN TELL, THE OPINION OF MOST OTHER ╞ORTH USERS, THE MOST SIGNIFICANT STANDARD SO FAR. ┴S A RESULT, IT IS NOT COMPLETELY COMPATIBLE WITH ╙TARTING ╞ORTH. ( ═R. ┬RODIES LATEST BOOK ╘╚╔╬╦╔╬╟ ╞╧╥╘╚ , USES ╞ORTH-83, BY THE WAY.)
╨ERHAPS SURPRISINGLY, MOST OF THE EXAMPLES ┬RODIE GIVES WORK WITHOUT A SINGLE CHANGE IN ┬LAZIN' ╞ORTH. ╘HIS DOCUMENT IS INTENDED TO HELP YOU WHEN THE EXAMPLES DON'T WORK AS DESCRIBED, SPEEDING UP THE LEARNING PROCESS, EASING THE PAIN, AND GENERALLY HELPING TO PREVENT YOU FROM DAMAGING YOURSELF OR YOUR COMPUTER THROUGH FRUSTATION. ─IFFERENCES BETWEEN THE EARLIER ╞ORTH'S AND THE PRESENT STANDARD ARE DESCRIBED, AND ALTERNATE DEFINITIONS ARE PROVIDED.
╬OT ALL THE COMMENTS ARE ABOUT DIFFERENCES - THERE ARE MANY MORE WORDS IN ┬LAZIN' ╞ORTH THAN ARE INCLUDED IN THE ╙TANDARD. ╔ COULDN'T RESIST TELLING YOU ABOUT A FEW OF THEM.
╟OOD LUCK! ┴ND MAY THE ╞ORTH BE WITH YOU.
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╙─┬
╬┘ ╬┘ 1985
Ç*FP0
Ç*CN1;├HAPTER 1Ç*CN0
╨AGE 11
╘HE DEFINITION ╙╘┴╥ WILL WORK AS SUPPLIED. ┬LAZIN' ╞ORTH CONTAINS A WORD CALLED ┴╙├╔╔ THAT CAN MAKE WORDS LIKE ╙╘┴╥ MORE READABLE (AND SAVE YOU A LOT OF TIME LOOKING UP CHARACTERS IN ┴╙├╔╔ TABLES). ╒SING ┴╙├╔╔ , THE DEFINITION OF ╙╘┴╥ WOULD BE:
: ╙╘┴╥ ┴╙├╔╔ * ┼═╔╘ ;
╘RY IT - YOU'LL LIKE IT.
┬Y THE WAY, IF YOU CHANGE THE DEFINITION OF ═┴╥╟╔╬ ON THE NEXT PAGE TO
: ═┴╥╟╔╬ ├╥ 15 ╙╨┴├┼╙ ;
YOUR LETTER WILL LOOK A LITTLE BETTER ON THE SCREEN.
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╘HE ─ICTIONARY ╨AGE-16
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┬LAZIN' ╞ORTH NORMALLY ALLOWS 31 CHARACTERS TO BE SAVED IN A DEFINITIONS NAME. (╘HIS IS THE NUMBER SPECIFIED BY THE 83 STANDARD.) ╚OWEVER, SHOULD YOU PREFER FEWER CHARACTERS TO BE SAVED, YOU CAN DO THIS BY CHANGING THE VALUE OF THE VARIABLE ╫╔─╘╚ . ╞OR EXAMPLE, TO HAVE ┬LAZIN' ╞ORTH SAVE ONLY THREE CHARACTERS OF YOUR DEFINITIONS NAMES, TYPE 3 ╫╔─╘╚ !
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╙AY-╫HAT?
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╥EGARDING THE SECOND FOOT-NOTE ON PAGE-18. ╘HE ╞ORTH-83 ." WILL NOT EXECUTE OUTSIDE OF A COLON DEFINITION. ╞ORTH-83 PROVIDES THE WORD .( FOR THE OCCASIONS WHEN YOU NEED TO DISPLAY STRINGS OUTSIDE OF COLON DEFINITIONS. ╒SE IT LIKE THIS:
.( ╨╥╔╬╘ ═┼ )
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Ç*CN1;├HAPTER-2Ç*CN0
Ç*LN2
╘HE HANDY HINT ON PAGE-50 IS A LITTLE NOTORIOUS. ╔ HAVE, PERSONALLY, NEVER SEEN A SYSTEM ON WHICH THIS DEFINITION WOULD WORK. .╙ IS NEVER THE LESS A VERY HANDY WORD, AND ┬LAZIN' ╞ORTH CONTAINS IT, ALREADY COMPILED INTO THE SYSTEM. ╬OTE THAT THE EXTRA 0 WON'T BE THERE - YOU SEE ONLY WHAT'S ON THE STACK, OR YOU GET A MESSAGE "╙╘┴├╦ ┼═╨╘┘", IF NOTHING IS ON THE STACK.
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Ç*CN1;├HAPTER-3Ç*CN0
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┬LAZIN' ╞ORTH'S EDITOR IS A "╙TARTING-╞ORTH-├LONE". ┘OU WILL BE ABLE TO FOLLOW THIS CHAPTER PRETTY MUCH AS IT STANDS. ╧NE VERY IMPORTANT POINT - YOU MUST ISSUE THE COMMAND ═╧╒╬╘ , TO INITIALIZE THE VIRTUAL MEMORY SYSTEM, BEFORE USING ANY WORDS THAT ACCESS THE DISK - LIKE ╠╔╙╘ , FOR EXAMPLE. ╩UST REMEMBER TO TYPE ═╧╒╬╘ , AND YOU WILL BE ╧╦ . (┘OU ONLY HAVE TO GIVE THIS COMMAND ONCE - AT THE START OF YOUR EDITING SESSION, UNLESS YOU CHANGE DISKS, ISSUE THE COMMAND ╥┼╙╘┴╥╘, OR INADVERTANTLY CAUSE A DISK ERROR.)
╙OME GENERAL POINTS: ┬RODIE LIKES TO KEEP HIS SCREEN NUMBERS HIGH - IN THE 100'S OR 200'S . ╬OTE THAT IF YOU HAVE A DUAL DRIVE, SUCH AS A 4040 OR ═╙─ , YOU WILL HAVE NO PROBLEM WITH THESE HIGH SCREEN NUMBERS ( OF COURSE, YOU WILL HAVE TO HAVE A DISK IN DRIVE 1!). ╚OWEVER, IF YOU ARE USING THE SYSTEM WITH A SINGLE DISK DRIVE, SUCH AS A 1541, THEN THE HIGHEST SCREEN THAT CAN BE ACCESSED FROM THAT DRIVE IS 165 . ╩UST KEEP ALL YOUR SCREEN NUMBERS BELOW THIS VALUE, AND YOU WILL BE ╧╦ .
╘HE ╫╔╨┼ COMMAND IS VERY IMPORTANT, NEVER EDIT A NEW SCREEN WITHOUT USING THIS COMMAND FIRST! ╔T'S SO IMPORTANT, THAT ┬LAZIN ╞ORTH CONTAINS THE WORD ╫ , WHICH IS JUST A SHORT WAY TO PERFORM A ╫╔╨┼ . ╫ORKS JUST THE SAME.
╞INALLY, DUE TO THE CHARACTERISTICS OF THE 64'S OPERATING SYSTEM, TRAILING BLANKS ARE SUPPRESSED, AND NOT PASSED TO THE EDITOR. ╘HIS MEANS, FOR EXAMPLE, THAT ┬RODIES EXAMPLE OF BLANKING A LINE:
╨ BB <RETURN>
WON'T WORK. ╘RAILING BLANKS MUST BE FOLLOWED BY AN ^ CHARACTER IN ORDER TO BE RECEIVED BY THE EDITOR. ╞OR EXAMPLE:
╨ BB^ ( BLANKS CURRENT LINE )
╒ BB^ ( BLANKS LINE UNDER CURRENT LINE)
╘HAT'S ENOUGH FOR NOW - CHECK BACK HERE WHEN YOU GET TO ╞╠╒╙╚.
╔N ╞ORTH-83, ╞╠╒╙╚ AND ╙┴╓┼-┬╒╞╞┼╥╙ ARE NOT QUITE THE SAME. ┬OTH SAVE ANY UPDATED BLOCKS TO THE DISK, BUT ╞╠╒╙╚ WILL "HOSE DOWN" THE BUFFERS - IF YOU WANT TO ACCESS THE SAME BLOCKS AGAIN, ╞ORTH WILL HAVE TO RE-READ THEM. ╙┴╓┼-┬╒╞╞┼╥╙ WILL LEAVE ALL THE BLOCKS CURRENT - ╞ORTH WON'T HAVE TO RE-READ THEM IF YOU NEED TO ACCESS THEM AGAIN. ┴LSO, ┬LAZIN' ╞ORTH CONTAINS AN ADDITIONAL COMMENT WORD, // , WHICH CAN BE USED TO INCLUDE 1 LINE COMMENTS IN SOURCE SCREENS.
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╟ETTING ╠OADED ╨AGE-81
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╘HE SUGGESTION HERE IS NOT REALLY VERY GOOD. ╔F THE SOURCE FOR YOUR TEXT TAKES UP MORE THAN ONE BLOCK, THE BEST SOLUTION IS NOT TO USE MANY LOAD COMMANDS, AS ┬RODIE SUGGESTS, BUT TO USE ╘╚╥╒ .
╘╚╥╒ TAKES TWO NUMBERS ON THE STACK. ╘HE FIRST NUMBER IS THE FIRST SCREEN TO LOAD, AND THE SECOND NUMBER IS THE LAST SCREEN TO LOAD. ╘╚╥╒ WILL THEN LOAD THESE TWO SCREENS, AND ALL SCREENS IN BETWEEN.
╙O, INSTEAD OF PUTTING 180 ╠╧┴─ 181 ╠╧┴─ 182 ╠╧┴─ ON YOUR LOAD SCREEN, USE:
180 182 ╘╚╥╒
INSTEAD. ╔T'S REALLY MUCH BETTER.
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Ç*CN1;├HAPTER 4Ç*CN0
Ç*LN3
┴ ├LOSER ╠OOK AT ╔╞ . ╨AGE-95
╧NE OF THE BIG DIFFERENCES BETWEEN THE 83 STANDARD AND EARLIER ╞ORTHS IS THAT ╞ORTH-83 RETURNS A NEGATIVE 1 ( -1 ) INSTEAD OF 1 WHEN THE RESULT OF A TEST LIKE 0= OR 0< IS TRUE. ╙O ┬RODIES EXAMPLES WILL LOOK LIKE THIS:
5 4 > . -1 ╧╦
5 4 < . 0 ╧╦
╬╧╘ WORKS DIFFERENTLY TOO. ╔N EARLIER ╞ORTHS, IT WAS REALLY JUST ANOTHER NAME FOR 0= . ┬UT IN ╞ORTH-83, IT RETURNS THE ONES-COMPLIMENT OF THE NUMBER ON THE TOP OF THE STACK. ╬OTICE THAT THE '83 ╬╧╘ STILL REVERSES THE VALUE OF THE '83 FLAGS:Ç*LN2
-1 ╬╧╘ . 0 ╧╦
0 ╬╧╘ . -1 ╧╦
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┬UT ╬╧╘ WON'T CHANGE ANY NON-ZERO VALUE TO FALSE ( 0 ) LIKE THE OLDER ╬╧╘ WOULD:Ç*LN2
1 ╬╧╘ . -2 ╧╦
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┴ND, OF COURSE, ╞╧╥╘╚ WILL STILL REGARD -2 AS BEING ╘╥╒┼ , SINCE IT ISN'T ZERO.
╙O WHEN UPGRADING PROGRAMS, OR READING BOOKS THAT TALK ABOUT EARLIER ╞ORTH SYSTEMS, KEEP THIS IN MIND. ╧N THE OTHER HAND, IF YOU'RE NOT QUITE SURE WHAT ALL THIS MEANS, AND WANT TO PLAY IT SAFE, JUST REPLACE EVERY PRE-83 ╬╧╘ WITH 0= , AND YOU'LL BE ╧╦ .
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┴ ╠ITTLE ╠OGIC ╨AGE-97
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╘O UPGRADE THESE EXAMPLES TO ╞╧╥╘╚-83, JUST REPLACE EVERY OCCURANCE OF 1 WITH -1 , AND YOU'LL HAVE A ╞ORTH-83 EXAMPLE. ╫HILE WE ARE ON THE SUBJECT, ┬LAZIN' ╞ORTH CONTAINS THE TWO FLAGS PRE-COMPILED AS CONSTANTS. ╘╥╒┼ LEAVES A TRUE VALUE (-1) ON THE TOP OF THE STACK, AND ╞┴╠╙┼ LEAVES A FALSE VALUE ( 0 ). ┘OU'LL APPRECIATE THIS MORE WHEN YOU LEARN ABOUT CONSTANTS LATER IN THE BOOK.
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╘WO ╫ORDS WITH BUILT IN ╔╞S ╨AGE 102
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╩UST A NOTE - IF YOU DO WANT TO ADD STACK CHECKING TO YOUR APPLICATION, ALL YOU NEED TO ADD IN ┬LAZIN' ╞ORTH IS THE WORD ?╙╘┴├╦ . ╘HE ┴┬╧╥╘" ISN'T NEEDED, SINCE ?╙╘┴├╦ ITSELF CONTAINS THE NECESSARY ┴┬╧╥╘" .
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╨ROBLEMS ╨AGE-104
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╨ROBLEM 5
┴CTUALLY, IN ╞ORTH-83, 0 ╙╘┴╥╙ WON'T PRINT JUST ONE STAR, BUT 65,535 STARS. ┬RODIES ANSWER ( OR THE ONE YOU COOK UP FOR YOURSELF) SHOULD FIX THIS PROBLEM, BUT THERE ARE BETTER WAYS. ═ORE ON THIS WHEN WE GET TO THE CHAPTER ON ╠╧╧╨S. ╔NCIDENTALLY, IF YOU TRIED 0 ╙╘┴╥╙ BEFORE READING THIS NOTE, YOU CAN GET CONTROL OF THINGS BY HITTING ╥╒╬/╙╘╧╨ ╥┼╙╘╧╥┼ , JUST LIKE IN ┬┴╙╔├ .
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├HAPTER-5
╘HE ╥ETURN ╙TACK
╨AGE-110
╘HE DEFINITIONS FOR ╔ , ╔' AND ╩ ARE NOT CORRECT FOR ╞ORTH-83. ╔' DOES NOT EXIST, AND ╔ AND ╩ ARE BOTH DEFINED DIFFERENTLY. ─ON'T WORRY, THEY STILL DO WHAT THEY ARE SUPPOSED TO (WHICH IS RETURN THE CURRENT INDEX VALUE OF A LOOP), IT'S JUST THAT THEY DON'T DO WHAT ┬RODIE SAYS THEY WOULD. ╩UST WAIT TILL CHAPTER 6 FOR MORE INFORMATION ON THESE TWO WORDS.
╘HE CORRECT WORD TO COPY THE TOP OF THE RETURN STACK IS ╥@ IN ╞ORTH-83. (I.E. ╥@ DOES WHAT ┬RODIE SAYS ╔ SHOULD DO.)
╨AGE-111
╘HE PHRASE >╥ ╙╫┴╨ ╔ WOULD BE >╥ ╙╫┴╨ ╥@ IN ╞ORTH - 83. ┬OTH PHRASES WILL CRASH THE SYSTEM
╨AGE-112
╘HE DEFINITION OF ╤╒┴─╥┴╘╔├ SHOULD BE:
: ╤╒┴─╥┴╘╔├ ( ┴ ┬ ├ ╪ -- ╬ )
>╥ ╙╫┴╨ ╥╧╘ ╥@ * + ╥> * + ;
╔N OTHER WORDS, ╥@ SHOULD BE USED INSTEAD OF ╔ . ╙EE THE NOTE ABOVE FOR AN EXPLANATION.
╨AGE-119
╘HE FOOTNOTE ON THIS PAGE CONTAINS A TYPO IN MY COPY. ╘HE CORRECT DEFINITION IS:Ç*LN2
: ╥% 50 */ 1+ 2/ ;
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╨ROBLEMS
╨ROBLEM 1
╔N THE ANSWER TO THIS PROBLEM, ┬RODIE MEANS ╬┼╟┴╘┼ , NOT ═╔╬╒╙ .
┘OU MIGHT ALSO NOTICE THAT ┬LAZIN' ╞ORTH DOES NOT RETURN A -17 LIKE ┬RODIE SAYS IT SHOULD. ╘HIS IS DUE TO THE 83-STANDARDS USE OF FLOORED DIVISION. ╔N FLOORED DIVISION, NUMBERS ARE ALWAYS TRUNCATED TO THE NEXT LOWER VALUE. ╘O GET THE SAME RESULT AS ┬RODIE IN 83-╞ORTH SYSTEMS, USE ┴┬╙ AND THEN ╬┼╟┴╘┼.
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Ç*CN1;├HAPTER 6Ç*CN0
Ç*LN2
╞ORTH-83 USES A NEW LOOP STRUCTURE WHICH IS VERY FAST, BUT DIFFERS IN A FEW POINTS FROM THE OLDER LOOPS USED IN OLDER ╞ORTHS. ╙ORRY ABOUT THIS, BUT THERE WILL BE A LITTLE MORE INFORMATION HERE THAN PREVIOUSLY.
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╨AGE-130
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┼ARLIER (IN THE NOTES TO CHAPTER 5) WE SAID THAT "╔" WORKS DIFFERENTLY IN '83 ╞ORTHS. ╫ELL, ORIGINALLY, "╔" WAS MEANT TO BE USED AS IT IS HERE, TO ACCESS THE LOOP INDEX. ╙INCE IN THOSE DAYS, THE LOOP INDEX WAS STORED ON THE TOP OF THE RETURN STACK, YOU COULD ALSO USE "╔" TO COPY THAT VALUE, EVEN IF YOU WEREN'T IN A LOOP, WHICH WAS NOT A PURPOSE FOR WHICH IT WAS ORIGINALLY INTENDED. ╙O THAT'S THE DIFFERENCE, ╔ NOW ONLY RETURNS THE LOOP INDEX, WHILE ╥@ COPIES THE TOP OF THE RETURN STACK TO THE PARAMETER STACK. (╞OR THE CURIOUS: ╔N ┬LAZIN' ╞ORTH, ╔ RETURNS THE SUM OF THE TOP TWO RETURN STACK ITEMS. ╔T MAY SEEM STRANGE, BUT IT WORKS JUST FINE!)
╘HE TERMINATING CONDITION FOR LOOPS IS ALSO DIFFERENT THAN IN EARLIER ╞ORTHS. ─ON'T BE FOOLED BY THE FACT THAT MOST OF THE EXAMPLES IN THIS CHAPTER WORK THE SAME - THE EXIT CONDITION FOR THE LOOPS ARE DIFFERENT, AND IF YOU IGNORE THIS FACT, YOU ARE GOING TO GET BIT BY IT.
╔N '83 LOOPS, THE LOOP IS FINISHED WHEN THE ╔NDEX CROSSES THE BOUNDARY BETWEEN THE ╠╔═╔╘ AND ╠╔═╔╘ - 1 . ┴ COUPLE OF EXAMPLES:
╔F THE ╔NDEX IS 0 , AND THE ╠╔═╔╘ IS 10 , THEN THE LOOP WILL TERMINATE WHEN THE ╔NDEX IS INCREMENTED FROM 9 TO 10 (CROSSES THE BOUNDARY).
╔F THE ╔NDEX IS 0 , AND THE ╠IMIT IS -10 , THEN THE LOOP WILL TERMINATE WHEN THE INDEX IS INCREMENTED FROM -11 TO -10 OR DECREMENTED FROM -10 TO -11 . ╘HIS MEANS, IF YOU ARE USING A ─╧..╠╧╧╨, THAT YOUR LOOP WILL TAKE THE LONG WAY AROUND...0 1 2 3 4 ...32767 -32768 .....-15 -14 -13 -12 -11 . ╔F YOU ARE USING +╠╧╧╨ WITH A NEGATIVE STEP VALUE, THEN YOUR LOOP WILL LOOK LIKE THIS: 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 (BOUNDARY CROSSED, AND LOOPED TERMINATED).
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╧NE ODD SIDE EFFECT OF THIS NEW LOOP STRUCTURE IS THAT ANYTIME THE LIMIT AND THE INDEX ARE EQUAL, THE LOOP WILL EXECUTE 65,535 TIMES. ╙O, FOR EXAMPLE, THE WORD ╙╘┴╥╙ :
: ╙╘┴╥╙ 0 ─╧ ┴╙├╔╔ * ┼═╔╘ ╠╧╧╨ ;
╔F USED LIKE THIS:
0 ╙╘┴╥╙
WILL ┼═╔╘ AN AWFUL LOT OF STARS. ┬LAZIN' ╞ORTH CONTAINS A WORD TO HANDLE CASES LIKE THIS - ?─╧ . ?─╧ ACTS JUST LIKE ─╧ , EXCEPT WHEN THE LOOP ARGUMENTS ARE EQUAL. ╔F THE ARGUMENTS ARE EQUAL, THEN THE LOOP WON'T BE ENTERED AT ALL - ╞╧╥╘╚ WILL JUMP TO THE WORD FOLLOWING ╠╧╧╨ OR +╠╧╧╨ . ╔N ADDITION TO KEEPING OUT NASTY SURPRISES (LIKE 0 ╙╘┴╥) ?─╧ CAN ALSO SHORTEN AND SPEED UP YOUR CODE. ╞OR EXAMPLE, WE OFTEN FIND WE DON'T WANT TO PERFORM A LOOP WHEN THE ╠╔═╔╘ IS ZERO (AS IN ╙╘┴╥╙ , ABOVE.) ╘HE TRADITIONAL WAY TO DO THIS IS:
: ╙╘┴╥╙ ?─╒╨ ╔╞ 0 ─╧ ┴╙├╔╔ * ┼═╔╘ ╠╧╧╨ ╘╚┼╬ ;
┬UT YOU CAN NOW DO IT THIS WAY:
: ╙╘┴╥╙ 0 ?─╧ ╔╞ ┴╙├╔╔ * ┼═╔╘ ╠╧╧╨ ;
┘OU CAN THINK OF ?─╧ AS HAVING A BUILT IN ╔╞ .
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╨AGE 135
╘HE DEFINITION GIVEN BY ┬RODIE:
: ╘┼╙╘ 100 10 ─╧ ╔ . -1 +╠╧╧╨ ;
WILL EXECUTE QUITE A FEW MORE TIMES THAN ONE (IN '83 ╞ORTH). ╥EMEMBER, '83 LOOPS STOP WHEN THE BOUNDARY IS CROSSED BETWEEN THE ╠╔═╔╘ AND ╠╔═╔╘-1 . ╘HIS CROSSING CAN BE IN EITHER DIRECTION, EITHER DOWN ( 101 100 (CROSSED TO 99, SO EXIT) ) OR UP ( 98 99 (CROSSED TO 100, SO EXIT)) . ╙INCE ╘┼╙╘ COUNTS DOWN, IT WILL PROCEED ALL THE WAY AROUND THE NUMBER CIRCLE, STARTING WITH 10, AND THEN GOING NEGATIVE, UNTIL IT EVENTUALLY GOES 101 100 (AS IN OUR FIRST EXAMPLE, ABOVE). ╩UST THOUGH ╔ WOULD MENTION THIS.
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╨AGE-140 ╠┼┴╓┼
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╔N '83 ╞ORTH, ╠┼┴╓┼ LEAVES IMMEDIATELY, NOT AT THE NEXT EXECUTION OF ╠╧╧╨ OR +╠╧╧╨. ┬RODIES EXAMPLES WILL WORK THE SAME FOR BOTH '83 AND EARLIER ╞ORTHS, BUT PROBLEMS CAN ARISE IF YOU AREN'T AWARE OF THE DIFFERENCE. ╞OR EXAMPLE:
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: ╞╧╧ 0 ─╧ ╔ ─╒╨ 100 = ╔╞ ╠┼┴╓┼ ╘╚┼╬ . ╠╧╧╨ ;
╞╧╧ IS A WORD THAT WILL EXIT WHEN THE LOOP COUNTER REACHES 100 . ╬OTICE, HOWEVER, THAT THE ACTUAL BEHAVIOUR OF ╞╧╧ WILL DIFFER BETWEEN '83 AND EARLIER STANDARDS. ╔N EARLIER ╞ORTHS, ╞╧╧'S EXECUTION WOULD BE THIS:
╫HEN THE ├OUNTER REACHES 100, ╠┼┴╓┼ WILL SET THE INDEX EQUAL TO THE LIMIT.
" . " WILL BE EXECUTED, PRINTING 100 ON THE TERMINAL SCREEN, AND LEAVING THE STACK EMPTY.
╠╧╧╨ WILL EXECUTE, AND DISCOVER ITS TIME TO STOP (SINCE ╠┼┴╓┼ CHANGED THE ╔╬─┼╪).
╔N '83 ╞ORTH, THIS IS WHAT HAPPENS.
╫HEN THE ├OUNTER REACHES 100, ╠┼┴╓┼ WILL JUMP TO THE WORD PAST ╠╧╧╨ , WHICH IN THIS CASE IS THE END OF THE DEFINITION. 100 WILL NOT BE PRINTED, BUT LEFT ON THE STACK. ╤UITE DIFFERENT BEHAVIOURS RESULT, AS YOU CAN SEE. ╩UST REMEMBER THAT THE 83 ╠┼┴╓┼ LEAPS , AND YOU'LL BE ╧╦ .
┬Y THE WAY, ┬LAZIN' ╞ORTH HAS A HANDY WORD ?╠┼┴╓┼ . ?╠┼┴╓┼ WILL CAUSE AN EXIT FROM THE LOOP IF THE FLAG ON TOP OF THE STACK IS TRUE, OTHERWISE, THE LOOP CONTINUES UNDISTURBED. ╘HIS CAN SHORTEN YOUR CODE QUITE A BIT. ╚ERE'S AN EXAMPLE:
: ┬┴╥ 0 ─╧ ╔ 100 = ╔╞ ╠┼┴╓┼ ╘╚┼╬ ╠╧╧╨ ;
╘HIS WORD JUST LEAVES WHEN THE INDEX REACHES 100. ╒SING ?╠┼┴╓┼ WOULD MAKE THINGS A LITTLE NICER:
: ┬┴╥ 0 ─╧ ╔ 100 = ?╠┼┴╓┼ ╠╧╧╨ ;
╫ORKS JUST THE SAME. ╩UST REMEMBER THAT YOU HAVE TO LEAVE A FLAG ON THE STACK FOR ?╠┼┴╓┼ TO EAT.
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Ç*CN1;├HAPTER 7Ç*CN0
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╙ECTION ╔╔
╨AGE 161
╘HE ╞ORTH-83 WORD FOR ╒* IS ╒═* . ╔T WORKS THE SAME AS ╒* , BUT HAS BEEN RENAMED.
╘HE ╞ORTH-83 WORD FOR ╒/═╧─ IS ╒═/═╧─ . ╔T WORKS THE SAME.
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/╠╧╧╨ IS NOT INCLUDED. ╔T IS NO LONGER NECESSARY IN '83 SYSTEMS. (╞OR THE CURIOUS: /╠╧╧╨ WAS ESSENTIALLY A KLUDGE TO FIX A PROBLEM WITH THE OLDER LOOPS. ╩UST USE +╠╧╧╨ INSTEAD.)
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╨AGE 164
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'83 SYSTEMS WILL ONLY ACCEPT THE PERIOD AS PUNCTUATION IN NUMBERS. ╚OWEVER, IN ┬LAZIN' ╞ORTH, YOU MAY CHANGE THIS. ╚ERE ARE THE STEPS TO FOLLOW TO GET ┬LAZIN' ╞ORTH TO ACCEPT THE SAME CHARACTERS THOSE GIVEN BY ┬RODIE:
╞IRST, TYPE IN AND ╠╧┴─ THE FOLLOWING DEFINITION:
: ╬┼╫-╨╒╬├╘ ( ├╚┴╥ -- ╞╠┴╟)
┴╙├╔╔ : ╧╓┼╥ = ╙╫┴╨
┴╙├╔╔ + ┴╙├╔╔ 0 >╥ ╧╓┼╥ < ╙╫┴╨ ╥> < ┴╬─ ╧╥ ;
╘HEN, ONCE YOUR ╬┼╫-╨╒╬├╘ HAS BEEN LOADED, TYPE THE FOLLOWING:
' ╬┼╫-╨╒╬├╘ ╔╙ ╨╒╬├╘?
╘YPE THE ABOVE CAREFULLY, OR YOU COULD CAUSE PROBLEMS (DON'T FORGET THE ' ). ┬LAZIN' ╞ORTH WILL NOW ACCEPT NUMBERS AS DESCRIBED IN THIS SECTION. ╔F YOU PREFER THIS NEW VERSION, YOU MAY SAVE THE SYSTEM WITH THE WORD ╙┴╓┼-╞╧╥╘╚. ╔F YOU WANT TO CHANGE BACK TO THE OOLDER VERSION, DO THE FOLLOWING:
' (╨╒╬├╘?) ╔╙ ╨╒╬├╘?
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╬UMBER ╞ORMATTING -- ─OUBLE ╠ENGTH ╒NSIGNED.
╨AGES 167-168
┴LL OF THE DEFINITIONS IN THIS SECTION WILL WORK AS DESCRIBED, BUT THEY WOULD BE SO MUCH MORE READABLE USING ┴╙├╔╔ . ╚ERE ARE SOME EXAMPLES:
╘HE DEFINITION THAT ┬RODIE GIVES FOR .$ WON'T WORK IN 83-FORTH. ╙╔╟╬ WORKS ON THE VALUE ON THE TOP OF THE STACK. ┴ DEFINITION THAT WILL WORK IN 83-╞ORTH IS:
: .$ ╙╫┴╨ ╧╓┼╥ ─┴┬╙
<# # # ┴╙├╔╔ . ╚╧╠─ #╙ ╥╧╘ ( TO BRING SIGNED NUMBER TO TOP)
┴╙├╔╔ $ ╚╧╠─ ╙╔╟╬ #> ╘┘╨┼ ╙╨┴├┼ ;
┘OU MIGHT ALSO NOTICW THAT THE POSITIONS OF THE $ AND ╙╔╟╬ HAVE BEEN SWITCHED. ╔ PREFER MY NEGATIVE DOLLARS TO HAVE THEIR SIGNS IN FRONT OF THE $ SIGN. ╘HAT'S THE ONLY REASON FOR THIS CHANGE.
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╨AGE 174
╘HE WARNING TO EXPERIMENTERS IS NOT TRUE IN ┬LAZIN' ╞ORTH. ┘OU CAN INCLUDE PUNCTUATED, DOUBLE-PRECISION NUMBERS INSIDE OF COLON DEFINITIONS, AND THEY WILL WORK JUST FINE. (╔ HAVE NEVER UNDERSTOOD THIS RESTRICTION.) ╬OTE THAT OTHER SYSTEMS MAY NOT ALLOW THIS.
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╨AGE 175
╘HE DEFINITION FOR ╥% ON THIS PAGE IS SIMPLY WRONG. ╔T SHOULD BE, INSTEAD:
: ╥% 10 ═*/ 5 ═+ 10 ═/ ╙>─ ╥╧╘ ─╥╧╨ ;
╫HICH GIVES $148.15 AS AN ANSWER.
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╨AGE 194
╙EE THE NOTE ABOVE (PAGE 174). ┘OU DO NOT NEED TO USE 2├╧╬╙╘┴╬╘ TO INCLUDE DOUBLE NUMBERS IN ┬LAZIN' ╞ORTH. ┘OU MAY WISH TO DO SO AS A MATTER OF STYLE, BUT IT IS NOT FORCED ON YOU.
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┬RODIES EXAMPLE:
110 ' ╠╔═╔╘ !
WON'T WORK WITH THE '83 TICK. ╒SE
110 ' ╠╔═╔╘ >┬╧─┘ !
INSTEAD. ┬Y THE WAY, ╠╔═╔╘ IS AN IMPORTANT SYSTEM CONSTANT IN ┬LAZIN' ╞ORTH, AND ╔ DON'T RECOMMEND THAT YOU TRY THIS EXAMPLE ON IT.
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╓ECTORED ┼XECUTION:
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╨AGE 218
╘HE BEHAVIOUR OF ' AND ['] IN '83 ╞ORTH IS EXACTLY THAT DESCRIBED HERE. ╔GNORE THE FOOTNOTE ON '79S TICK. ┘OU MIGHT ALSO WISH TO LOOK AT THE DOCUMENTATION FOR ─┼╞┼╥ ╔╙ , WHICH ARE VERY HANDY WORDS FOR HANDLING ╓ECTORED ┼XECUTION.
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╘HE ╙TRUCTURE OF A ─ICTIONARY ┼NTRY.
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╨AGE 220
╘HE STRUCTURE OF A DICTIONARY ENTRY FOR ┬LAZIN' ╞ORTH THAN DESCRIBED HERE. (╬OTE: ╘HE '83 STANDARD REGARDS THIS AS A SYSTEM DEPENDENCY, AND DOES NOT SPECIFY ANY PARTICULAR FORM OF DICTIONARY STRUCTURE. ╧THER SYSTEMS MAY, AND PROBABLY DO, DIFFER.)
╔N ┬LAZIN' ╞ORTH, THE STRUCTURE IS:
╠╔╬╦ ╞╔┼╠─
╬┴═┼ ╞╔┼╠─
├╧─┼ ╨╧╔╬╘┼╥ ╞╔┼╠─
╨┴╥┴═┼╘┼╥ ╞╔┼╠─
╘HERE IS ALSO AN OPTIONAL FIELD, CALLED THE ╓╔┼╫ OR ╠╧├┴╘┼ FIELD. ╘HIS FIELD IS USED BY ╠╧├┴╘┼, AND IS ADDED OR NOT AT THE OPTION OF THE USER. ╫ITH THE VIEW FIELD INCLUDED, THE STRUCTURE LOOKS LIKE THIS:
╓╔┼╫ ╞╔┼╠─
╬┴═┼ ╞╔┼╠─
├╧─┼ ╨╧╔╬╘┼╥ ╞╔┼╠─
╨┴╥┴═┼╘┼╥ ╞╔┼╠─
├OMPILING WITHOUT THE ╓╔┼╫ ╞╔┼╠─ RESULTS IN MORE COMPACT (BUT NOT FASTER RUNNING) DEFINITIONS, BUT NOTE THAT ╠╧├┴╘┼ WILL NOT OPERATE ON ANY DEFINITION WITHOUT A ╓╔┼╫ ╞╔┼╠─. ╘O PREVENT THE VIEW FIELD FROM BEING COMPILED:
╓╔┼╫ ╧╞╞
╘O RE-ENABLE THE COMPILATION OF THE ╓╔┼╫ ╞╔┼╠─:
2 ╓╔┼╫ !
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╨ARAMETER ╞IELD
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╨AGE 223
╘HE ADDRESS RETURNED BY TICK AND EXPECTED BY ┼╪┼├╒╘┼ IS NOT THE PARAMETER FIELD ADDRESS, BUT THE ├╧─┼ ╞╔┼╠─ ADDRESS. ╔F YOU WANT THE PARAMETER FIELD ADDRESS, YOU MAY CONVERT THE ADDRESS RETURNED BY TICK (THE CODE FIELD ADDRESS) TO THE PARAMETER FIELD ADDRESS USING THE '83 STANDARD WORD >┬╧─┘ . ╞OR AN ILLUSTRATION OF ITS USE, SEE THE EXAMPLE USING ╠╔═╔╘ , GIVEN EARLIER.
