Stephen, thanks for the link! The paper was an interesting read and definitely gave me some ideas. Tillmann -- you are correct in that it's very similar to a database. I frequently go through this process: 1) Receive a flat file (various formats) of tabular data 2) Create a model of the data and a parser for the file 3) Code utilities that allow business users to filter/query/accumulate/compare the files The models are always changing, so one option would be to inspect a user-supplied definition, build a SQLite database to match, and use Haskell to feed in the data and run queries. However, I'm usually dealing with files that can easily be loaded into memory, and generally they aren't accessed with enough frequency to justify persisting them in a separate format. It's actually worked fine in the past to code a custom data type with record syntax (or sometimes just tuples) and simply build a list of them, but the challenge in taking this to a higher level is reading in a user-supplied definition, perhaps translated as 'the first column should be indexed by the string "Purchase amount" and contains a Double', and then performing calculations on those doubles based on further user input. I'm trying to get over bad object-oriented habits of assigning attributes at runtime and inspecting types to determine which functions can be applied to which data, and I'm not sure what concepts of functional programming better address these requirements. On Fri, May 27, 2011 at 12:33 PM, Tillmann Rendel < rendel@informatik.uni-marburg.de> wrote:
Hi,
Eric Rasmussen wrote:
The spreadsheet analogy isn't too literal as I'll be using this for data with a more regular structure. For instance, one grid might have 3 columns where every item in column one is a CellStr, every item in column two a CellStr, and every item in column 3 a CellDbl, but within a given grid there won't be surprise rows with extra columns or columns that contain some cell strings, some cell ints, etc.
Sounds more like a database than like a spreadsheet.
Tillmann
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe