On scoping the project: be clear about the actual goal. If you want to take existing Haskell libraries and use them in OCaml, then you pretty much have to deal with the full language. You should start by using as much as you can of an existing compiler, or by getting an unmodified compiler to convert source code to "Core" syntax. As just one example, a recent thread concerned implementing lock-free containers. I don't expect converting one of those to OCaml to be easy... If, however, you want to make it possible for someone to write code in a sublanguage of Haskell that is acceptable to a Haskell compiler and convert just *that* to OCaml, you might be able to produce something useful much quicker. It has long been my opinion that the TV series "Butt-Ugly Martians" was inspired by OCaml syntax. I keep being attracted by other features of OCaml, but unable to bring myself to use its syntax. (I have much the same problem with F#, and if SML.NET -- www.cl.cam.ac.uk/research/tsg/SMLNET/ -- had been updated in the last nearly 6 years I would not be looking at F# at all.) Never mind popularising Haskell to OCaml users; this could be a way of popularising OCaml to Haskell users. One of the reasons Harrop gives for preferring F# to OCaml is that F# supports true multicore concurrency, while OCaml apparently still doesn't.