CODEWITHSUNDEEP
haskell
Jeff Maner
Jeff Maner

Reputation: 1179

Haskell Error "Not in scope: data constructor"

I've reviewed the other posts on this error, and I don't think I'm making any of those mistakes.

Not in scope: data constructor 'Extraction'.

Configuration.hs:

module Configuration
(Config
 , columns
 , headers
 , types
 , totals
 , extractions,
 Extraction
 , xState
 , xDivisions
 , xOffice
 ...) where

...

data Extraction = Extraction { xState     :: String
                             , xDivisions :: Maybe [String]
                             , xOffice    :: Maybe String } deriving Show


data Config = Config { columns     ::  String
                     , headers     :: [String]
                     , types       :: [String]
                     , totals      :: [String]
                     , extractions :: [Extraction] } deriving Show

...

PIF.hs:

module PIF (...) where

import Configuration

...

data Report = Report { division  :: String
                     , state     :: String
                     , office    :: String
                     , inSection :: Bool
                     , content   :: [String] } deriving Show

...

extract :: Config -> [Report] -> [Report]
extract c = filter f
  where f Report { division=d, state=s, office=o, inSection=_, content=_ } =
          map or $ map isMatch $ extractions c
          where isMatch
                  | Extraction { xState=xS, xDivisions=Just xD, xOffice=Nothing } = s==xS && (map or $ map (==d) xD)
                  | Extraction { xState=xS, xDivisions=Nothing, xOffice=Just xO } = s==xS && o==xO

Let me know if you need more information. Thanks.

Here is my corrected extract:

extract c = filter f
  where f Report { division=d, state=s, office=o, inSection=_, content=_ } =
          or $ map isMatch $ extractions c
          where isMatch x =
                  case ((xDivisions x), (xOffice x)) of (Nothing, Just y) -> s==(xState x) && o==y
                                                        (Just y, Nothing) -> s==(xState x) && (or $ map (==d) y)

Upvotes: 7

Views: 2081

Answers (1)

sclv
sclv

Reputation: 38893

Change the export line Extraction to Extraction(..).

Without that, you're exporting the type but not the data constructor. Since your type and constructor share the same name, this is less than obvious in this case.

Upvotes: 15

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