How can I force MediaWiki to respect single line breaks?

mediawiki, php

Solution

Use https://www.mediawiki.org/wiki/Extension:Poem

<poem>
Roses are red
Violets are blue
</poem>

Problem

By default, MediaWiki ignores single line breaks, treating them as a single space. To insert a new line in a page, you must insert two consecutive line breaks in the source, which results in a new paragraph: `</p><p>`. It's also possible to insert `<br />` directly into the source. How can I modify the MediaWiki parsing engine so single line breaks in the source are replaced automatically with a `<br />` in the resulting HTML? (Source: http://www.mediawiki.org/wiki/Help:Formatting)

Original source