Env-parser does a few things to make handling ENV easier. First, it, through virtue of Haskell's IO-concentration properties, forces you to pre-load your relevant environment variables and thus fail-fast due to misspellings and poor parses. Second, it tries to force you to interpret the ENV strings as typed values so that there's a limitation of the syntactic space allowable in ENV files.
Finally, and most importantly, it uses an "applicative functor structure" so that the exact code which parses your ENV can be used to produce documentation automatically. This is nice because it will always be in-sync with your program (modulo errors in my own coding of the library).
If anyone is interested in using this in their Haskell code, I'd be more than happy to push out the newer version. It has much nicer parsers and better reporting.
[0] http://hackage.haskell.org/package/env-parser [1] https://github.com/tel/env-parser-talk