Landon Curt Noll
4ee4c731f7
While not strictly necessary, replacing the two ASCII tab characters in the markdown copyright comment makes it easier to detect problematic TAB indentation within markdown files. After this commit, only 90 markdown files have leading ASCII TAB characters. And again, while not strictly necessary, we can consider running expand on those 90 markdown files to see what effect that might have on the HTML files they produce. Replace leading ASCII TAB characters with multiples of 8 ASCII SPACE characters (the default action of the `expand(1)` tool) might have an negative effect on some HTML formatting where **hack-a-round** formatting was attempted to fix broken indentation caused by problematic ASCII TAB characters. Think of this as a baseline for evaluating leading TAB characters within markdown files. TODO: Consider either using `expand(1)` to replace leading ASCII TAB characters with multiples of 8 ASCII SPACE characters AND/OR modifying the appropriate `bin` tool to convert leading ASCII TAB characters into multiples of 8 ASCII SPACE characters.
86 lines
2.1 KiB
Markdown
86 lines
2.1 KiB
Markdown
## To build:
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``` <!---sh-->
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make
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```
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## To use:
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``` <!---sh-->
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./prog
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```
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## Try:
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``` <!---sh-->
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./try.sh
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```
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By default that will use `indent(1)` found by the shell `type -P indent` and
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`sed(1)` found by the shell `type -P sed` but if you want to change these, say
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to try a different beautifier, you can do it like:
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``` <!---sh-->
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INDENT=bcpp ./try.sh
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```
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which would change it to use `bcpp(1)` instead of `indent(1)`. Do similar for
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`sed(1)` only use the name `SED`.
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## Judges' remarks:
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C11 features definitely help this entry to be as concise as it is.
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The judges would like to think that they had almost understood how this entry works.
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If you win a bet by demonstrating this entry, please let us know.
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## Author's remarks:
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### Remarks
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- Computes the factorial function.
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- No loops, no explicit recursion.
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- Untyped C without any casts, using a `w` word datatype.
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- Varargs not essential, `w(*)(w,w*)` works just as well.
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- Conforming to ISO C.
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- No warnings when compiled with `-std=c99 -Wall -Wextra -pedantic`.
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- Comments in the code explain what this really is about.
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- C as a functional programming language: untyped lambda calculus compiled to
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executable C functions.
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- Untagged closures (just a function pointer followed by some values).
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- Recursion implemented through Curry's paradoxical combinator `Y`.
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- The readable implementation of `Y` is on lines 29-30:
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```
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W_f = \x.f(xx)
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Y = \f.W_f W_f
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```
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- A mixture of strict and lazy evaluation, with a `_` force function
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(John Tromp notes that if Turing's fixed-point combinator
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`(\xy.y\z.xxyz)(\xy.y\z.xxyz)` had been used,
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all applications could have been strict).
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- Uses `Y` to implement factorial on native `int`s.
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- 10! seconds = 6 weeks.
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- Answers the [ultimate question of life, the universe and
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everything](https://hitchhikers.fandom.com/wiki/42).
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<!--
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Copyright © 1984-2024 by Landon Curt Noll. All Rights Reserved.
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You are free to share and adapt this file under the terms of this license:
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Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)
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For more information, see:
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https://creativecommons.org/licenses/by-sa/4.0/
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-->
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