I think it is worth taking the risk to use a relatively unusual and unproven technology.
should be:
I think it is worth taking the risk to use a relatively unusual technology.
Why is using Haskell a risk? It's not a proprietary system where the company might shut down.
It would be interesting to know if the devs there are long time haskell developers, or if new hires could easily be trained in haskell.
Looks really interesting. I wrote an SQL parser and compiler frontend for a SQLite-style database last summer. I started off in C using Lex/Yacc, but for the last piece of the project I used Haskell. This step was to take SRA ("sugared relational algebra"), which is essentially a transition step between SQL and simple relational algebra, and desugar it into relational algebra. The code is up at https://github.com/thinkpad20/sql if anyone is interested, with the code for that portion being contained in the haskell folder. I might translate the whole thing into Haskell (maybe using Attoparsec) at some point.
I was curious that you used a different version of relational algebra than the one I had been taught. I've usually seen RA described in terms of six fundamental operators: Project (pi), Select (sigma), Rename (rho), Cross Product, Union and Difference. What gave rise to the model you chose?
Anyway, it's great to see that more people are using Haskell. I would love to be able to work in it some day.