Yesod is a Minimal Web Framework

Software developers have a natural affinity for minimalism. This manifests itself in a number of ways. It might be removing unnecessary work to make some code path more performant. It might be an effort to adhere to the Single Responsibility Principle. It might be elegance. It might be a Divide and Conquer strategy to reduce the programmer’s cognitive load.

It’s no surprise then that programmers would be naturally drawn to libraries and frameworks that are billed as minimal. But simply stripping things away is not the essence of minimalism.

Minimalism is about being deliberate in your choice of things to keep ownership of. It’s about consciously choosing what you would like to control, and what you would like to delegate away.

In the Haskell world, we have a decent selection of web frameworks. Yesod is typically recognised as one of the more batteries included frameworks, and this becomes a reason for many developers to avoid it. The sentiment is usually “Oh, I’m just throwing together a simple JSON API. I don’t need any of the other stuff it provides.”

I think this sentiment is short-sighted. There are a number of foundational components to any web application that you will need regardless of how complex you anticipate your project will be. A great example is logging. Every web application needs decent logging, and unless logging is an interesting part of the software you’re writing — spoiler alert: it probably isn’t — there’s no real value in starting without that component and adding it afterwards.

Yesod also provides templating, application state, routing, and potentially database access if you choose to scaffold your project that way. It’s always easier to start with some reasonable defaults for these mundane aspects of your system and later strip away what you don’t need, than it is to start with nothing and gradually piece together your grand architecture.