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Infix pattern matching

By : Arun Govindaraju
Date : September 15 2020, 10:00 PM
wish of those help I don't believe there is (or can be) an infix operator, because a pattern isn't a value; it's syntax.
You are looking for a case expression
code :
toHex :: Color -> String
toHex color = case color of
               Greyscale _ -> something
               otherwise -> somethingElse
toHex :: Color -> String
toHex (Greyscale _) = something
toHex _ = somethingElse
{-# LANGUAGE LambdaCase #-}

toHex :: Color -> String
toHex = \case 
          Greyscale _ -> something
          otherwise -> somethingElse

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awk extended pattern matching (embedding pattern matching in actions for already matched strings)

By : Paolo
Date : March 29 2020, 07:55 AM
Any of those help Not quite in that way, but pretty close, as there is a regular expression match operator (~):
code :
BEGIN { FS="," }
            if ($1 ~ "TYPE_1") {printf "[TYPE1] [DATA: $2]"}    // <-- included pattern 
            if ($1 ~ "TYPE_2") {printf "[TYPE2] [DATA: $2]"}    // <-- another included pattern
            ...                                        // <-- some more included patterns
BEGIN { FS="," }
/PREFIX/ { //stuff to do for all prefixes, before specific handling
          data = $2 }
/PREFIX_TYPE_1/ { type = "TYPE_1"; }
/PREFIX_TYPE_2/ { type = "TYPE_2"; }
/PREFIX/ { //stuff to do for all prefixes, after specific handling 
          printf("[%s] [DATA: $2]", type, data)

How can I `find` files matching pattern within a directory matching another pattern from the command line?

By : James
Date : March 29 2020, 07:55 AM
Hope that helps You use a wildcard in the -name parameter but you can also use it in the path parameter.
code :
find /Path/bar* -name "file_name*"
|-- bar
    `-- file_name123.txt
|-- bar1
    `-- file_name234.txt
|-- bar2
    `-- file_name345.txt
|-- foo
    `-- file_name456.txt

Scala pattern matching guard breaks pattern matching exhaustiveness?

By : sai krishna Thota
Date : March 29 2020, 07:55 AM
This might help you It looks like this is an open issue.
A comment by Adriaan Moors:

Search lines with matching Pattern in File but replace string matching with second pattern in same line

By : K Battersby
Date : March 29 2020, 07:55 AM
hop of those help? Need help from Shell/Bash Geeks especially on Mac OS , You could likely do it with something simple, like so:
code :
sed -i 's/VAL15\(.*STRING-REPLACE-VAL\)/VAL20\1/'
sed -E '/STRING-REPLACE-VAL/bx ; b ; :x ; s/VAL15/VAL20/ ;'

How does this case class definition allow infix pattern matching?

By : Johny Bols
Date : March 29 2020, 07:55 AM
I wish this help you I recently wrote a parser using scala's parser combinator library. I decided I was curious about the implementation, and went digging. ,
Do case classes provide [unapply] by default (I think yes)?
code :
%%> cat srcfile.scala
class XYZ(arg :Int)
%%> scalac -Xprint:4 srcfile.scala > plainClass.phase4
%%> vi srcfile.scala  # add “case” 
%%> scalac -Xprint:4 srcfile.scala > caseClass.phase4
%%> diff plainClass.phase4 caseClass.phase4
class XX(val c:Char, val n:Int)
object XX {
  def unapply(arg: XX): Option[(Char, Int)] = Some((arg.c,arg.n))

val a XX b = new XX('g', 9)
//a: Char = g
//b: Int = 9
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