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1 yapp stands for "yet another program printer", or "yet another
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2 printing program", or maybe "yet another printer printer". yapp is a
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3 program that prints out programs that print out.
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4
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5 That is, yapp takes whatever is piped into its standard input, and
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6 produces on its standard output the source code for an INTERCAL
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7 program that will, when compiled, produce the original file. The
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8 created program will be self-contained; it will not need the system
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9 library to compile. The reason for this is to maximize the amount of
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10 data that yapp can encode into an INTERCAL program. The current
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11 compiler has an upper bound on the number of commands one program can
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12 have; thus yapp will not produce a compilable program if given more
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13 than 3880 bytes.
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14
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15 Though yapp was intended to create standalone programs, it can also be
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16 used to generate subroutines. (In fact, the first working version of
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17 this program was used to generate the lines for the final draft.) In
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18 such a case, it is convenient to specify what character the data will
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19 "follow". The easiest way to accomplish this is to replace the "DO .9
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20 <- #0" in line 22 with "DO .9 <- <num>", where <num> is the
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21 bit-reversed code of the character preceeding the data (#80 in the
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22 case of a newline, for example). A more versatile modification is to
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23 change line 22 to "DO WRITE IN .9", and then insert the character code
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24 at the top of the file that is to be fed to yapp. Thus, if the data in
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25 the file would follow a newline, the line "EIGHT OH" would be added to
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26 the top of the data file.
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