I am currently learning about pattern matching algorithms and have come across these two algorithms. I have the following general ideas: KMP Compares text left-to-right Uses a failure array to s...

So I'm writing a simple method that sums up the first 3 or less ints in a list but i'm confused about the match patterns. I currently have let sums l = match l with | [] -> 0 | (h1::h2::h3::_...

I came across this JS code snippet: function append(demo = "", file = "") { const extra = "ctl=1&embed=1"; if (demo && file) return `/${demo}/?file=${fil...

I would like to do some multiline matching with bash's =~ #!/bin/bash str='foo = 1 2 3 bar = what about 42? boo = more words ' re='bar = (.*)' if [[ "$str" =~ $re ]]; then echo "${BASH_REMATCH[1]...

I have following data in table: +----------------------+----------------------------------------------------------+--------------+ | subscriber_fields_id | name | field_type | +-------------------...

Is there a way to 'pull' data out of an Option? I have an API call that returns Some(HashMap). I want to use the HashMap as if it weren't inside Some and play with the data. Based on what I've read...

How can I count the number of "_" in a string like "bla_bla_blabla_bla"?

I downloaded the release candidate of JDK19 from here https://jdk.java.net/19/ to play a little bit with the new record patterns that were implemented there, but I'm encountering some issues. In my...

I'm looking for a way to test whether or not a given string repeats itself for the entire string or not. Examples: [ '0045662100456621004566210045662100456621', # '00456621' '007299270072992700...

I like to use pattern-matching on a nullable int i.e. int?: int t = 42; object tobj = t; if (tobj is int? i) { System.Console.WriteLine($"It is a nullable int of value {i}"); } However, this r...

I want to apply filter on an iterator and I came up with this one and it works, but it's super verbose: .filter(|ref my_struct| match my_struct.my_enum { Unknown => false, _ => true }) I w...

Learning Scala 3. how can i make this code type-match and compile? trait Key { type Value } object Name extends Key { type Value = String } object Age extends Key { type Value = Int } type D...

I'm trying to take an arbitrary tuple of Futures and return a tuple of the completed future's values, while providing a time limit for the completion of the futures. I'm trying to use Tuple's provi...

Here is a simple example: object MatchErasedType { trait Supe { self: Singleton => type T1 lazy val default: T1 def process(v: Any): T1 = { v match { case vv: T1 => vv case _ =&gt...

I'm trying to zip tuples together and use match types to get the exact type of the resulting zip. I have a match type and the function: type Z[A <: Tuple, B <: Tuple] <: Tuple = (A, B) ma...

Is there a way to generate a number sequence in vi or Vim? For example, for an arbitrary range of lines i  through j (where i < j) in a file opened in Vim, is there a way to generate a number se...

I'm learning about regular expression. I don't know how to combine different regular expression to make a single generic regular expression. I want to write a single regular expression which...

The new structural pattern matching feature in Python 3.10 is a very welcome feature. Is there a way to match inequalities using this statement? Prototype example: match a: case < 42: print('L...

I want to switch through many possible cases for x and there's one case (here x == 0) where I want to check the result of some additional code to determine what to do next. One possibility is to re...

Everybody says that pattern matching is a great feature in functional languages. Why? Can't I simple use ifs and switch cases for everything? I'd like to understand the advantages of using patter...

In rust you can do things like this: for n in 1..101 { let triple = (n % 5, n % 2, n % 7); match triple { // Destructure the second and third elements (0, y, z) => println!("First is `0...

Consider this: loop { let data = match something() { Err(err) => { warn!("An error: {}; skipped.", err); continue; }, Ok(x) => x }; let data2 = match something_else() { Er...

My table has 650M rows (according to a fast but decently precise estimate from a query I found here). It has a text column called receiver_account_id, and I need to be able to search those records ...

With pgAdmin III, I can list all the databases on my postgresql server. But with pgAdmin, I can delete only 1 database at the time. It takes a lot of time to delete, for example, 30 databases, on...

I am having 4 strings: "h:/a/b/c" "h:/a/b/d" "h:/a/b/e" "h:/a/c" I want to find the common prefix for those strings, i.e. "h:/a". How to find that? Usually I'd split the string with delimiter '...