lift-formlets is a functionally-pure, form-handling library for the Lift Web application framework. It is based around the idea, as described in this paper, that with the right choice of abstractions, Web forms can and should be easily and infinitely composable.
lift-formlets makes heavy use of Scalaz's
Applicative, but it is not necessary to understand the details of how they work to successfully validate and compose forms. For those interested however, Functional Programming in Scala cannot be more highly recommended.
Formality is another form building library for Lift. It has a tasteful, well-documented API that integrates more tightly with the standard Lift way of doing things than does lift-formlets. Formality and lift-formlets share the common goal of leveraging Lift's CSS selector transforms as much as possible to bind the dynamic portions of a form to an existing template. Parts of the template binding code in lift-formlets are based on Formality.
Formaggio is a now-abandoned implementation of Formlets in Scala. lift-formlets doesn't share any code with Formaggio and the details are ultimately very different, but it was still incredibly helpful to find another Formlet library that also used Scala and Scalaz.