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Joined 1 year ago
Cake day: June 9th, 2023
  • fubo@lemmy.worldtoProgrammer Humor@lemmy.ml•Oh boy what a beautiful regex. I'm sure it does something logical and easy to understand.
    11·
    17 days ago

    Regex is good for a few very specific things, and sysadmins used to use it for goddamn everything. If all your server logs are in lightly-structured text files on a small number of servers, being able to improvise regex is damn useful for tracking down server problems. Just write a shell loop that spawns an ssh logging into each server and running grep over the log files, to look for that weird error.

    These days, if you need to crunch production server logs you probably need to improvise in SQL and jq and protobufs or systemd assmonkery or something.

    But if you actually need a parser, for goodness sake use a parser combinator toolkit, don’t roll your own, especially not with regex. Describing your input language in plain Haskell is much nicer than kludging it.

    (This is the “totally serious software engineering advice” forum, right?)

  • fubo@lemmy.worldtoProgrammer Humor@lemmy.ml•Oh boy what a beautiful regex. I'm sure it does something logical and easy to understand.
    135·
    16 days ago

    The answer given in the spoiler tag is not quite correct!

    Test case

    According to the spoiler, this shouldn’t match “abab”, but it does.

    Corrected regex

    This will match what the spoiler says: ^.?$|^((.)\2+?)\1+$

    Full workup

    Any Perl-compatible regex can be parsed into a syntax tree using the Common Lisp package CL-PPCRE. So if you already know Common Lisp, you don’t need to learn regex syntax too!

    So let’s put the original regex into CL-PPCRE’s parser. (Note, we have to add a backslash to escape the backslash in the string.) The parser will turn the regex notation into a nice pretty S-expression.

    > (cl-ppcre:parse-string "^.?$|^(..+?)\\1+$")
(:ALTERNATION
 (:SEQUENCE :START-ANCHOR (:GREEDY-REPETITION 0 1 :EVERYTHING) :END-ANCHOR)
 (:SEQUENCE :START-ANCHOR
  (:REGISTER
   (:SEQUENCE :EVERYTHING (:NON-GREEDY-REPETITION 1 NIL :EVERYTHING)))
  (:GREEDY-REPETITION 1 NIL (:BACK-REFERENCE 1)) :END-ANCHOR))

    At which point we can tell it’s tricky because there’s a capturing register using a non-greedy repetition. (That’s the \1 and the +? in the original.)

    The top level is an alternation (the | in the original) and the first branch is pretty simple: it’s just zero or one of any character.

    The second branch is the fun one. It’s looking for two or more repetitions of the captured group, which is itself two or more characters. So, for instance, “aaaa”, or “abcabc”, or “abbaabba”, but not “aaaaa” or “abba”.

    So strings that this matches will be of non-prime length: zero, one, or a multiple of two numbers 2 or greater.

    But it is not true that it matches only “any character repeated a non-prime number of times” because it also matches composite-length sequences formed by repeating a string of different characters, like “abcabc”.

    If we actually want what the spoiler says — only non-prime repetitions of a single character — then we need to use a second capturing register inside the first. This gives us:

    ^.?$|^((.)\2+?)\1+$.

    Specifically, this replaces (..+?) with ((.)\2+?). The \2 matches the character captured by (.), so the whole regex now needs to see the same character throughout.

  • fubo@lemmy.worldtoProgramming@programming.dev•White House: Future Software Should Be Memory Safe
    18·
    9 months ago

    Rust does memory-safety in the most manual way possible, by requiring the programmer prove to the compiler that the code is memory-safe. This allows memory-safety with no runtime overhead, but makes the language comparatively difficult to learn and use.

    Garbage-collected compiled languages — including Java, Go, Kotlin, Haskell, or Common Lisp — can provide memory-safety while putting the extra work on the runtime rather than on the programmer. This can impose a small performance penalty but typically makes for a language that’s much easier on the programmer.

    And, of course, in many cases the raw performance of a native-code compiled language is not necessary, and a bytecode interpreter like Python is just fine.

  • fubo@lemmy.worldtoProgramming@programming.dev•*Permanently Deleted*
    65·
    9 months ago

    Some other ways:

    Cultivate bitterness.

    Find the pessimists in your organization, and disappoint them.

    Make mean cynicism a part of your workplace culture. Do this by example: Promote mean cynics and put them in charge of things. But do it also by conversion: Behave in a way that makes mean cynics’ view of the world correct.

    Reward bad personal habits to create internal conflicts between work and health.

    If someone skips sleep to finish a project, give them a bonus. This gives them an internal conflict between approval and health, and teaches them that they can sacrifice their health to receive a reward.

    Encourage a hard-drinking culture in teams that have stressful roles that demand team cohesion, like SRE or Ops teams with on-call requirements. This gives them an internal conflict between their support network and health.

    If someone is sick, injured, bereaved, or otherwise suffering: Make it clear how much their condition is inconvenient to their coworkers, and how much their projects are impacted by their absence. Assure them that all will be well once they can conclude their personal problems and commit to the team. Do not, however, offer them any specific help; if they express specific needs for accommodation, disregard them as idle and unrealistic wishes.