We present a generic type inference algorithm for Hindley/Milner style
systems based on Constraint Handling Rules (CHRs). We are able to
model Haskell-style type classes, records in style of Ohori and
overloading in style of System O and System CT. Inference algorithms
for each of the above systems can be derived by providing the
appropriate CHRs and primitive functions.
 
In previous work, we have introduced a general type class framework on
CHRs.  There, we focused on the study of theoretical properties such
as decidable type inference. In this work we provide some practical
evidence of our approach. We have actually implemented the CHR-based
type inference algorithm (in Haskell) including a simple user
interface which allows to design your own type system.  We give an
overview of the expressiveness of our system by example.