capital letter name in record syntax (parsing json)
Hi, please,...is it possible to use a capital letter in record syntax data definition? For example data Car = Car { CarName :: !Text ,CarColor :: !Text } deriving (Show,Generic) When I try this I get: parse error on input `CarName' The thing is that I'm trying to parse a json file (with Aeson package) that has records starting with capital letter. After that I would like to parse the JSON file with following code: d <- (eitherDecode <$> getJSON) :: IO (Either String [Car]) where getJSON gets the json file from url If not, what alternative do I have? thanks, m.
On Wed, Oct 16, 2013 at 2:18 PM, Miro Karpis
Hi, please,...is it possible to use a capital letter in record syntax data definition? For example
data Car = Car { CarName :: !Text ,CarColor :: !Text } deriving (Show,Generic)
When I try this I get: parse error on input `CarName'
Record field names cannot start with a capital letter. Haskell uses the case of the first letter of a name to classify it: variables start with a lowercase letter; constructors start with an uppercase letter.
The thing is that I'm trying to parse a json file (with Aeson package) that has records starting with capital letter. After that I would like to parse the JSON file with following code:
d <- (eitherDecode <$> getJSON) :: IO (Either String [Car])
where getJSON gets the json file from url
If not, what alternative do I have?
If you generate your aeson instances with Data.Aeson.TH.deriveJSON, note that the first parameter to deriveJSON is a function which lets you alter the names. That should enable you to craft a workaround. -Karl
On Thu, Oct 17, 2013 at 4:18 AM, Miro Karpis
Hi, please,...is it possible to use a capital letter in record syntax data definition? For example
data Car = Car { CarName :: !Text ,CarColor :: !Text } deriving (Show,Generic)
What Karl said. You can prefix an underscore however: _CarName, _CarColor. -- Kim-Ee
participants (3)
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Karl Voelker -
Kim-Ee Yeoh -
Miro Karpis