Re: [Haskell-cafe] api-tools questions

Chris, thank you for the pointer, that is really helpful indeed! I see that you are using Haskell types for some fields, rather than types defined in your API. When I, for instance, try to use Map as field type, with String as both key and value type, I get an error: myrec :: MyRec // a map = record myfield :: Map String String Exception when trying to run compile-time code: Syntax error at line 345, column 20 (@8596): [(AlexPn 8596 345 20,TypeIden "String"),(AlexPn 8603 345 27,TypeIden "String")] I suspect this is only the case with types that are parameterized over others, as a type synonym seems to make this possible anyways. Is there a better way to deal with this than the one I mentioned? Thanks for your help, karsten Chris Dornan writes:

You might also find the keystore[0] package useful as it makes use of This technique in several places. See, for example the definition of Pattern in the `Data.Keystore.Types.Schema`[1] and `Data.Keystore.Types`[2].

Chris

[0] http://hackage.haskell.org/package/keystore [1] https://github.com/cdornan/keystore/blob/master/src/Data/KeyStore/Types/Sch ema.hs#L179 [2] https://github.com/cdornan/keystore/blob/master/src/Data/KeyStore/Types.hs# L68 [3] http://hackage.haskell.org/package/keystore-0.5.0.4

On 09/09/2014 17:20, "Karsten Gebbert" wrote:

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Excellent, thanks a lot Adam. I'll open a PR when I'm through with this project :)

Adam Gundry writes:

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Hi Karsten,

This isn't very well documented, but there is a (hidden) feature of api-tools that should do what you want. If you say something like

mt :: MyTime = basic string with inj_MyTime, prj_MyTime

then you can define your own type MyTime and give conversion functions inj_MyTime and prj_MyTime to convert back and forth from a newtype-wrapped Text. (In fact, you could probably use UTCTime as MyTime...). More precisely, api-tools will generate something like

newtype REP__MyTime = REP__MyTime Text

and you will need to implement

inj_MyTime :: REP__MyTime -> ParserWithErrs MyTime prj_MyTime :: MyTime -> REP__MyTime

I hope this helps, and further questions or documentation contributions are very welcome!

Cheers,

Adam

On 09/09/14 14:02, Karsten Gebbert wrote:

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Hi All,

I have a question concerning the api-tools package.

Its not clear from the tests, sources or the tutorial how I can use other date/time formats that the default `utc` type can handle. I'm trying to wrap a JSON API that is not under my control, so I have to adhere to whatever I get back from it. Could anybody with experience with the package point me to some example, relevant bits in the sources or a tip how to do it?

I'm planning to create some more documentation around the package to contribute back once I figured out a few more details, because I think its quite a useful abstraction when dealing with (foreign) APIs IMO.

Thanks already for any hints,

karsten

-- Adam Gundry, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/

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