Derive Reason types to interact with a Haskell backend.

Please see the README on GitHub at https://github.com/abarbu/servant-reason#readme

Servant Reason

Automatically derive bindings for Servant APIs in Reason. Originally build by converting servant-elm to Reason. Types are generated using reason-export.

More docs on Hackage.

A full example of how to integrate Servant and Reason is available at servant-reason-example.

Usage

Run the tests if you want a concrete example. They will build a _test-cache directory that contains a sample Reason repository for a servant API. test also contain example output files for different kinds of bindings.

Usage is simple and automatic. If you have an API like the one below

{-# LANGUAGE DataKinds         #-}
{-# LANGUAGE DeriveGeneric     #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE TypeOperators     #-}

import           Reason          (Spec (Spec), specsToDir, toReasonDecoderSource,
                               toReasonTypeSource)
import           GHC.Generics (Generic)
import           Servant.API  ((:>), Capture, Get, JSON)
import           Servant.Reason  (ReasonType, Proxy (Proxy), defReasonImports,
                               generateReasonForAPI)

data Book = Book
    { name :: String
    } deriving (Generic)

instance ReasonType Book

type BooksApi = "books" :> Capture "bookId" Int :> Get '[JSON] Book

You can expose your API to reason with:

module Main where

import Data.Proxy
import Reason
import           Data.Text hiding (intercalate, map)
import Db

main :: IO ()
main = do
  let code = defReasonImports
             : toReasonTypeSource    (Proxy :: Proxy Book)
             : toReasonDecoderSource (Proxy :: Proxy Book)
             : generateReasonForAPI  (Proxy :: Proxy BooksApi))
  writeFile "Api.re" $ intercalate "\n\n" $ map unpack code

That's it. You can now include Api.re in a Reason project.

Reason setup

The generated code needs access to two Reason libraries @glennsl/bs-json and bs-fetch. Get the latest install instructions from the upstream repos, but at the time of writing these were:

npm install --save @glennsl/bs-json
npm install --save bs-fetch

Then add @glennsl/bs-json and bs-fetch to bs-dependencies in your bsconfig.json:

{
  ...
  "bs-dependencies": ["@glennsl/bs-json", "bs-fetch"]
}