Title: Curry Generator 1 Category: Programming Lang: en Date: 2017-01-25 Tags: elm, random, curry, functional programming

Warning: Skip this one, if you want articles with substance and are not interested in meta ramblings.

Curry is great

The book

Shortly after my colleague and good friend Gregor introduced me to functional programming, I was looking for a good book to further give me an introductory peek into this topic. I chose the Curry Buch by Stefanie Schirmer, Hannes Mehnert und Jens Ohlig, I am not sure how I found out about it (Sorry for the german link, the book is supposed to be translated on the future though!). I was very happy with my choice, it is a great book and a fun read. Some of the content seem to be a little to academic to be useful for a beginner, but learning something new without having an immediate use for it is not a bad thing in my mind! And after briefly getting to know two of the authors at last years Bobkonf I now know that their knowledge about curry matches what they know about programming.

The generator

But that's not what this is about. As an introduction the book the authors use a curry generator, which generates random curry recipes from a list of ingredients. Though I was not able to try all combinations yet, I am sure they are all tasty. Because this program seems simple as well as extensible I chose it as my first playground to get to know Elm. The first version was only supposed to generate a recipe, the next one you were able to save a generated recipe. You had a lot of need for randomness, yet another reason this is a nice project to get to know functional programming. Though it might be tough to appreciate the resulting headache.

Randomness in purely functional languages

In the beginning I was not aware what a problem randomness is in a language which tries to remove side effect as far as possible from your view (which is one of the core features I love about Elm). If my program consists of mainly pure functions I want them to be predictable. By definition I don't want them to produce random results. This was the first mind bender I experienced, which made it abundantly clear to me that functional programming would be quite different from the way I was used to think about programming.

Current status

By the way, you can find the Curry Generator here. What are seeing here is written in Elm 0.16. Due to quite extensive changes in the way randomness is produced in current versions I never bothered to upgrade it. But I will do that soon, so stick around for updates.