My function is relatively simple and using fairly standard libraries:
{-# LANGUAGE OverloadedStrings #-}
module Foo where
import Conduit
import Data.CSV.Conduit
textToCSV :: Text -> Vector (MapRow Text)
textToCSV txt = replicateC 1 txt
.| intoCSV defCSVSettings
.| sinkVector & runConduitPure & runIdentity
I'd like to understand why I'm getting these type errors, and a solution would be great too:
* No instance for (CSV Text (Vector (MapRow Text)))
arising from a use of `intoCSV'
* In the first argument of `(.|)', namely `intoCSV defCSVSettings'
In the second argument of `(.|)', namely
`intoCSV defCSVSettings .| sinkVector'
In the first argument of `(&)', namely
`replicateC 1 txt .| intoCSV defCSVSettings .| sinkVector'
|
156 | .| intoCSV defCSVSettings
| ^^^^^^^^^^^^^^^^^^^^^^
* No instance for (Data.Vector.Generic.Base.Vector
Identity (Vector (MapRow Text)))
arising from a use of `sinkVector'
* In the second argument of `(.|)', namely `sinkVector'
In the second argument of `(.|)', namely
`intoCSV defCSVSettings .| sinkVector'
In the first argument of `(&)', namely
`replicateC 1 txt .| intoCSV defCSVSettings .| sinkVector'
|
157 | .| sinkVector & runConduitPure & runIdentity
| ^^^^^^^^^^
Certainly, I can agree that an instance of CSV Text Text
doesn't exist. But compared to what I'm doing, the typical usage using sourceFile
seems to have a very similar usage. I'm just as confused about the second error regarding vectors.
Possible workaround:
Not really an answer to the question, but a workaround I found (that is also more succinct) was to replace my textToCSV
function and several other auxiliary functions in the construction of my processCSV
conduit:
processCSV :: (MonadResource m, MonadThrow m, PrimMonad m) =>
ConduitT FilePath Void m (Vector (Vector (MapRow Text)))
processCSV = mapMC (readCSVFile defCSVSettings) .| sinkVector