Creating a Generative Type Provider

In my recently released Pluralsight course, Building F# Type Providers, I show how to build a type provider that uses erased types. To keep things simple I opted to not include any discussion of generative type providers beyond explaining the difference between type erasure and type generation. I thought I might get some negative feedback regarding that decision but I still believe it was the right decision for the course. That said, while the feedback I’ve received has been quite positive, especially for my first course, I have indeed heard from a few people that they would have liked to see generated types included as well.

There are a number of existing type providers that use generated types, most notably in my opinion is the SqlEnumProvider from FSharp.Data.SqlClient. That particular type provider generates CLI-enum or enum-like types which represent key/value pairs stored in the source database.

Although SqlEnumProvider is a great example and is relatively easy to follow, general how-to documentation for generative type providers is hard to come by to say the least. As such I thought that showing how to write the ID3Provider built in the course as a generative type provider would be a nice addendum for the course material. I clearly won’t be covering everything I do in the course here so if you’re looking for a deeper understanding of type providers I strongly encourage you to watch it before reading this article. (more…)


Building F# Type Providers on Pluralsight!

I was wrapping up The Book of F# and discussing the foreword with Bryan Hunter, he asked if I’d like to be connected to some of the folks at Pluralsight to discuss the possibility of an F# course. I agreed and a few days later I was on the phone brainstorming course ideas with them.

Of everything we discussed I was really only excited about a few topics enough to think I could put together a full course for them. Naturally the ones I was most excited about were already spoken for so I started trying to think of some other ideas. At that point I sort of fizzled out from seemingly endless distractions like changing jobs, speaking at a variety of events, and so on. Over the course of a few months I’d pretty much forgotten about the discussions. Fortunately for me, Pluralsight hadn’t forgotten and my acquisitions editor emailed me to see what happened.

We soon started talking again and one of the ideas I was originally excited about was now available and I’d been working on a related conference talk so I had the start of an outline. After a few iterations I was ready to start recording my Building F# Type Providers course.

Fast forward to earlier this week when I noticed some blog traffic from an unexpected source – my Pluralsight author profile page! I quickly discovered that my course was live!


If you’re wanting to learn more about one of F#’s most interesting features, I invite you to watch the course where I show a few existing type providers in action before walking through creating a simple type provider for reading the ID3 tag from an MP3 file using the Type Provider Starter Pack.