https://blog.augustfeng.app/tags/elm/ Recent content in Elm on August Feng Hugo en Sun, 04 Feb 2024 00:00:00 +0000 https://blog.augustfeng.app/articles/elm-type-variables/ Sun, 04 Feb 2024 00:00:00 +0000 https://blog.augustfeng.app/articles/elm-type-variables/ <div id="outline-container-headline-1" class="outline-2"> <h2 id="headline-1"> About </h2> <div id="outline-text-headline-1" class="outline-text-2"> <p> In the Elm In Action book, Richard Feldman writes:</p> <blockquote> <p>A command that produces no messages has the type Cmd msg, a sub- scription (for example, Sub.none) that produces no messages has the type Sub msg, and a list that has no elements—that is, []—has the similar type List val.</p> </blockquote> <p> The lower casing of <code>msg</code> signifies a <em>type variable</em>. Type variables are Elm&#39;s implementation of generics.</p> <p> The idea of a value being possible for a non concrete type felt odd to me, so I&#39;ve opt to explore this concept in other languages where I&#39;m more familiar with.</p>