cats-parse graph query language experiment - hello world 2 / published by https://github.com/dacr/code-examples-manager #896d5781-e750-48af-802b-6fd6a109ecb5/844c69900abd30321c43b6e9db14a7f3f012f1bc

catsparse-hello-2.sc

// summary : cats-parse graph query language experiment - hello world 2
// keywords : scala, typelevel, cats-parse, hello-world, @testable
// publish : gist
// authors : David Crosson
// license : Apache License Version 2.0 (https://www.apache.org/licenses/LICENSE-2.0.txt)
// id : 896d5781-e750-48af-802b-6fd6a109ecb5
// created-on : 2025-03-13T14:11:45+01:00
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.6.4"
//> using dep "org.typelevel::cats-parse:1.1.0"
//> using dep "com.lihaoyi::pprint:0.9.0"
// ---------------------

import cats.parse.{Parser0,Parser}
import cats.parse.Rfc5234.{lwsp, alpha}

case class Who(name: String)

val helloToken = Parser.ignoreCase("hello").surroundedBy(lwsp)

val helloParser: Parser0[Option[Who]] =
  (lwsp *> helloToken *> lwsp *> alpha.rep.string.? <* lwsp)
    .map(name => name.map(Who.apply))

val results = List(
  "hello david",
  " hello joe  ",
  " hello   ",
  "hello"
).map(s => helloParser.parseAll(s))

pprint.pprintln(results)