Custom separator does not seem to be working

[apraga]

Hi,

When trying the tutorial, using a custom separator does not seem to work :

With ml-100k/u.user containing

1;24;M;technician;85711
2;53;F;other;94043

The following code outputs nothing

module Main where

import qualified Control.Foldl                 as L
import qualified Data.Foldable as F
import           Frames
import Frames.TH (rowGen, RowGen(..))

tableTypes' (rowGen "ml-100k/u.user")
            { rowTypeName = "U2"
            , separator = ";"}

loadRows :: IO (Frame U2)
loadRows = inCoreAoS (readTable "ml-100k/u.user")

main = do
  ms <- loadRows
  mapM_ print (F.toList  ms)

Replacing ";" in the data file and in the code recognize the columns. Am I doing something wrong ? Using GHC 9.2.8 and Frames 0.7.3. Thanks,

[acowley]

This is rather opaque. Since we need a special parser for this table and its associated row type, we must make use of a definition tableTypes' quietly provides for us, u2Parser :: ParserOptions, that you must then pass to readTableOpt. So, you write loadRows = inCoreAoS (readTableOpt u2Parser "ml-100k/u.user"). What's happening is that custom separator is being used for parsing the file to generate the types at compile time, but then readTable is using the default parser at runtime.

[acowley]

For this data, it may also be helpful to provide column names. I don't think these are accurate, but it's what I threw together when testing this:

tableTypes' (rowGen "test/data/ml-100k/u.user")
            { rowTypeName = "U2"
            , columnNames = ["index", "age", "sex", "title", "zip"]
            , separator = ";"}

[apraga]

Thanks for the answer, it works perfectly. Do you think the documentation could be updated to reflect that ?

[acowley]

Yes, definitely. I was looking at how hls can expand splices in place, and it does show the various definitions, but it’s no substitute for documentation.