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The most surprising Unix programs

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Re: The most surprising Unix programs

#31

Post by indigochill »

cmroanirgo wrote: post #18
znpy wrote: post #16

It's surprising that Doug McIlroy still reads and writes about UNIX. For those who don't know, Dough is the guy that invented pipes.

Also interesting: > Originators of nearly half the list--pascal, struct, parts, eqn--were women, well beyond women's demographic share of computer science.

In the 40s, computing was seen as primarily women's work (similar to the stereotype of switchboard operators). Into the 60s, women still comprised up to half of the computing workforce. In 84, they peaked at 37%. So demographically speaking, the ratio was not as bad as it is today.

(Source: https://en.wikipedia.org/wiki/Women_in_computing)

Re: The most surprising Unix programs

#32

Post by davidwihl »

qubex wrote: post #4
morelisp wrote: post #3

> struct - Brenda Baker undertook her Fortan-to-Ratfor converter against the advice of her department head--me. I thought it would likely produce an ad hoc reordering of the orginal, freed of statement numbers, but otherwise no more readable than a properly indented Fortran program. Brenda proved me wrong. She discovered that every Fortran program has a canonically structured form. Programmers preferred the canonical…

I had to look up ‘Ratfor’ because I’d never heard of it — apparently it’s a FORTRAN preprocessor that added control structures.

One of the books that most influenced my coding was Software Tools by Brian W. Kernighan, P.J. Plauger [0]. Even though I never used Ratfor, the clear descriptions were immensely useful.

[0] https://www.goodreads.com/book/show/515603.Software_Tools

Re: The most surprising Unix programs

#33

Post by sn41 »

One of the useful applications of trigram-based analysis I have done is the following: for a large web-based application form where about 200000 online applications were made, we had to filter out the dummy applications - often, people would try out the interface using "aaa" as a name, for example.

Since the names were mostly Indian, we did not even have a standard database of names to test against.

What we did was the following: go through the entire database of all applications, and build a trigram frequency table. Then, using that trigram table, do a second pass over the database of names to find names with anomalous trigrams - if the percentage of trigram frequency anomaly in a name was too high (if the name was long enough), or the absolute number of trigrams in name was too high (if the name was short), we flagged the application and examined it manually. Using this alone, we were able to filter out a large number of dummy application forms.

Of course, it is not a comprehensive tool since what forms a valid name is very vague, but I think this kind of a tool is useful and culture-neutral.

Re: The most surprising Unix programs

#37

Post by amelius »

sn41 wrote: post #33

One of the useful applications of trigram-based analysis I have done is the following: for a large web-based application form where about 200000 online applications were made, we had to filter out the dummy applications - often, people would try out the interface using "aaa" as a name, for example. Since the names were mostly Indian, we did not even have a standard database of names to test against. What we did was t…

The problem with these methods is that you exclude everybody that deviates from the norm. Yes, it might make your life (as a developer) a little bit easier, but it makes the lives of some of the applicants a lot harder.

Re: The most surprising Unix programs

#38

Post by nicoburns »

thaumasiotes wrote: post #15
saagarjha wrote: post #7

And people say theoretical computer science isn’t useful in “the real world”… I am curious about this one, though, has anyone used it? > The syntax diagnostics from the compiler made by Sue Graham's group at Berkeley were the mmost helpful I have ever seen--and they were generated automatically. At a syntax error the compiler would suggest a token that could be inserted that would allow parsing to proceed further. No…

> On the surface it sounds a lot like it would produce error messages like “expected ‘;’” that most beginner programmers come to hate Do people really come to hate these? I'd expect the opposite -- that people would start off hating messages like "expected ';'", but fairly quickly become accustomed to what they almost always mean. As long as you can look at the message and have a good idea of what's wrong, it's not a…

Once you've used a compiler like Rust or Elm that actually provides suggestions for common solutions to these errors (effectively building the tribal knowledge of what the error "really means" into the compiler itself), it's hard to tolerate these cryptic errors that only really make sense to machines.

Re: The most surprising Unix programs

#39

Post by pimlottc »

nunoferreira wrote: post #35

What about "comm" - compare two sorted files line by line. You can easily get occurrences only in file 1, in both files, only in file 2. Super powerful and saved me hours of work.

comm is a really useful tool, with one big caveat — you must make sure your input files are all sorted the exact same way. If not, you can get unexpected results, and worse, might not even realize it.

This may seem obvious, but there are many tiny ways that sorts can differ between locales, operating systems and programs (e.g. Excel), especially when dealing with Unicode. It may look the same 99% of the time, and you may not realize until later that you’ve accidentally filtered out values.

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