# Functional Sets Course
**URL:** https://discourse.elm-lang.org/t/functional-sets-course/673
**Category:** Show and Tell
**Created:** [February 12, 2018, 2:18pm UTC](https://discourse.elm-lang.org/t/functional-sets-course/673 "2018-02-12T14:18:50Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@brian](https://discourse.elm-lang.org/u/brian)
#### Post date: [February 12, 2018, 2:18pm UTC](https://discourse.elm-lang.org/t/functional-sets-course/673/1 "2018-02-12T14:18:50Z")
Hey there! I’ve just put the finishing touches on and published a new course based on some blog posts I wrote over the last year.
In it, you’ll learn how to replicate the `Set` API. If you’re interested in how to create your own data structures in Elm, you’ll probably be pretty interested!
> **[Functional Sets](https://www.brianthicks.com/guide/functional-sets/)**
>
> In this series of guides, I show you how to build a functional data structure using Elm.
> Our goal: …
(p.s. this is the first set of posts I’ve turned into guides, which I’m going to be keeping up-to-date for Elm 0.19 and beyond.)
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### Author:  [@Atlewee](https://discourse.elm-lang.org/u/Atlewee)
#### Post date: [February 17, 2018, 11:22am UTC](https://discourse.elm-lang.org/t/functional-sets-course/673/2 "2018-02-17T11:22:51Z")
I have not seen this before now.
This was very well written.
I learned a lot reading through this. Not just about sets, but also how map/filter/fold++ works in general. 👍