Problem Statement

The goal is to verify the presence of a word or regular expression within several paragraphs of text (structured or not) and to format the output of the relevant paragraphs before putting them on the standard output. So here, let’s imagine that we are trying to verify the presence of a keyword "SystemError" within what I want to call "the paragraphs" "Traceback (most recent call last):" in the file Traceback.txt The expected result must be formated with ---------------- for paragraph's separator AND "Traceback (most recent call last):" as the beginning of each relevant's paragraph :

Let's start with the solution:

import "io" for File
import "./pattern" for Pattern

var fileName = "Traceback.txt"
var p1 = Pattern.new("Traceback (most recent call last):")
var p2 = Pattern.new("SystemError")
var sep = "----------------"

File.read(fileName)
    .split("\n\n")
    .where { |para| p1.isMatch(para) && p2.isMatch(para) }
    .each { |para|
        var ix = p1.find(para).index
        System.print(para[ix..-1])
        System.print(sep)
    }