When comparing Play Framework vs Yesod, the Slant community recommends Play Framework for most people. In the question“What are the best backend web frameworks?” Play Framework is ranked 10th while Yesod is ranked 14th.
Ranked in these QuestionsQuestion Ranking
Pro Asynchronous Core
Pro Interoperable with Java
It's like Java, but more Haskell-y.
Pro Play is an extensive ecosystem
Play uses Akka for concurrency, Scala for a templating engine, Netty as a client-server framework and SBT (Simple Build Tool) for building. And they all come out of the box.
Play also comes with the option to scaffold your applications. Play is an all-embracing ecosystem designed to increase developer productivity and shorten development times.
Pro Good documentation and a great community
Play has quite a large community which provides numerous tutorials and videos related to developing with Play.
The Play official documentation covers many things, such as the framework itself but also specific stuff such as Akka, SBT and Netty.
There are also many big companies that base their main sites around Play, one of them is LinkedIn which provides third-party documentation on a regular basis.
Pro Simple for beginners
Play is very simple to get started. The documentation is very helpful for beginners and advanced users alike and the official website has a great "Getting Started" tutorial to begin developing with Play.
Pro Readable code
Play framework's convention over configuration methodology makes most Play projects have a very similar structure. This means that the code written for the framework is very readable. This enables a developer to switch between applications without having to relearn the ecosystem for every project. The built-in templating system also helps with code and makes it possible to have a very low count of lines of code.
Pro Good Websocket Support
Pro Can use Java, one of the most widely known languages
Java is one of the most widely known languages, so people coming from that background can jump right in and not have to learn a new language syntax.
Pro Uses type-safe URLs
Ensures that data provided by the URL is type-safe. This means that data in the URL has a definitive type.
Pro Offers templating for type-safe, well-formed content
While not required, Yesod offers templating through a Shakespearean family of languages to produce page code.
Pro Can be used without knowing much Haskell
While Yesod is written in Haskell, developers can achieve basic functionality without much investment in the language.
Con Not as many resources to learn
Other languages and frameworks have countless tutorials, books, moocs, etc. Java and Play does not have nearly as much.
Con Backward incompatibility
The jump from Play 1 to Play 2.x caused a lot of confusion. While it is important to have some kind of evolution, sometimes it causes backward incompatibility which can create some problems. It makes tutorials or modules made for the old version obsolete. This can make it hard for beginners to find useful resources. The template engine which used Groovy now uses Scala.
Con Is hard to customize
Learning how Yesod works internally is hard. It is a large framework with complicated components. Finding the appropriate code and understanding how it contributes to the framework is difficult, meaning developers will struggle.
Con Too much template haskell
You actually want to code in haskell and not some DSL with "magic" hidden under the bonnet.