Parquet for Haskell

WIP attempt to write a parser for Parquet.

NB. this is a sideproject and is still extremely rough (and reflects the exploratory style of development).

To run - copy the customer.impala.parquet file to the dist/build/parquet directory and then use cabal run. Right now it will spit out a bunch of metadata read.

TODO

• Properly handle errors (as opposed to coercing types, etc).
• Implement parsers for the common encoding formats (e.g. RLE and BitPacking) so we can decode the repetition and definition levels.
• Switch to a better data type than Handle (basically we need random IO). Handle has a few problems at the moment (e.g. unless you force the parsing using a bang - it can try and resolve it after you have already moved the pointer resulting in an exception: parquet: thread blocked indefinitely in an MVar operation).
• Write a more complete TODO list (...)