188 lines
4.0 KiB
Markdown
188 lines
4.0 KiB
Markdown
```
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/* _ _ _
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| | / | / /
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| |__| ||__ _ _ __ __ _ / /
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| '_ | |/ ' | '_ \ / _' | / /
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| \_|| | || | | | | /_| | /_/
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\___/_____/___| |__,_ / _
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|____/ */
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```
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# blang!
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the bang language
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Public domain. 2022 DTB.
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Bang language is an unpleasant toy designed to be used in the murderu.us IRC
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server, but easily adapted anywhere due to its simplicity both in terms of
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model and implementation.
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## Glossary
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### chart
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The listing of the program currently running.
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This can be modified during runtime.
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### command
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A character that indicates what the bang language executor should do next.
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### comment
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Ornamental characters, i.e. in-code notes.
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Comments can start with `';'` (in which case they're discarded from the chart)
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or `'#'` (in which case they're kept on the chart).
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Comments end with `'!'` or `'\n'`.
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### hand
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The general-purpose register.
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### catch
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To set the hand to a value.
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### throw
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To set a value to the contents of the hand.
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## Reference
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All operations are one character long.
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When an unknown operation is executed the resulting behavior is undefined
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(and maliciously so; for example, execution can stop or garbage can be written
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to the chart).
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Operation mappings are based on ergonomics and history.
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`'&'` and `'*'` are taken from C.
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`'+'` and `'-'` are taken from Brainfuck.
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`'<'` and `'>'` are more or less taken from the Bourne shell.
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The general ergonomics of bang language are informed by the story of Mel,
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part of hacker folklore.
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### `'!'`
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No-op. Does nothing.
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`' '`, `'\n'`, `'\r'`, `'\t'`, and `'\v'` are all also no-ops
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\- keep this in mind when styling code that contains `'?'`!
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### `'#'`
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Denotes a comment.
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The contents of the comment are kept in the chart but not executed.
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### `';'`
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Denotes a comment.
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The contents of the comment are discarded from the chart before runtime.
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### `'^'` and `'%'`
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`'^'` palms the content of the location of the program to which chart points.
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`'%'` throws at that location.
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The following program prints "Hello, world!",
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by iterating over the program listing itself and terminating after printing a
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line feed (10 decimal in ASCII):
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```
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!Hello, world!
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{
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&+*
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^>
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----------?}; subtract 10, if the value is non-zero return
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vv*
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```
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### `'&'` and `'*'`
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`'&'` (et) palms the chart. `'*'` (splat) throws the chart.
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The following program rewrites itself during runtime, navigating the chart
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using et and splat. Keep in mind `'!'` must be followed by `';'` in comments
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to maintain chartlessness:
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```
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!vv; zero out hand
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{?>; set return point; if hand is non-zero, print hand
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!&; palm the chart
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++++*; add 4 to palm; splat the new chart
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<!%; write '!;' to the new chart position
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&++*; palm the chart; add 2 to palm; splat the new chart
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<<%; write '<' to the new chart position
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&+*; advance the chart one space
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<
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%; write '\n' to the new chart position
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&+*; advance the chart one space
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<>%; write '>' to the new chart position
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&+*; advance the chart one space
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<v%; write 'v' to the new chart position
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&+*; advance the chart one space
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<v%; write 'v' to the new chart position
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<!; palm '!;'
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}; return
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```
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Right before the final `'}'`, the chart is the following:
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```
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!vv; zero out hand
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{!>; print hand
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<
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>; palm `'\n'`; print hand
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vv*; splat zero to chart
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The rest of the program isn't executed.
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```
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### `'<'` and `'>'`
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`'<'` palms the next character literal.
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`'>'` prints the literal contents of hand to standard output.
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The following program prints "Hello, world!" the easy way:
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```
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!<H><e><l><l><o><,>< ><w><o><r><l><d><!>v++++++++++>v*
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```
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This is a quine; a program that prints itself.
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```
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{&+*!^>v?}v*
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```
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The following program prints the printable ASCII space:
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```
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!^*{; palm bang (the first printable ASCII char), splat
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&>+*; et, throw onto screen, increment, splat
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------
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------; subtract 126
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v?}; if hand == 0, return
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<
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>; print newline
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vv*; exit
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```
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