My first ugly working Haskell program, making an HTTP request w/ hard-coded JSON to retrieve data from Replicon's old RepliConnect API.

remote-api.hs

import Network.HTTP
import Network.URI
import Data.Either

data InstanceInfo =
    InstanceInfo {
        apiURL :: URI,
        companyKey :: String,
        loginName :: String,
        password :: String
    }

makeRequest :: InstanceInfo -> String -> IO (Either String String)
makeRequest info body =
    do  resp <- simpleHTTP request
        case resp of
            Left connError -> error "ERROR" --connError
            Right realResp -> do
                case rspCode realResp of
                    code@(1, _, _) -> error $ "1xx: " ++ (show code)
                    code@(2, _, _) -> error $ "2xx: " ++ (show code)
                    code@(3, _, _) -> error $ "3xx: " ++ (show code)
                    code@(4, _, _) -> error $ "4xx: " ++ (show code)
                    code@(5, _, _) -> error $ "5xx: " ++ (show code)
                    otherwise -> error "?"
    where request = Request { rqURI = apiURL info,
                              rqMethod = POST,
                              rqHeaders = [
                                mkHeader HdrContentType "application/json",
                                mkHeader HdrContentLength (show $ length body)
                              ],
                              rqBody = body }

main =
    do
        putStrLn "Hello, world!"
        case parseAbsoluteURI("https://na1.replicon.com/a/RemoteApi/RemoteApi.ashx/8.25.7/") of
            Nothing -> error "Unable to parse hard-coded API URL"
            Just uri -> do
                let info = InstanceInfo { apiURL = uri,
                    companyKey = "somecompanykey",
                    loginName = "someloginname",
                    Main.password = "somepassword" }
                val <- makeRequest info "{ \"Action\": \"GetSystemPreferences\" }"
                case val of
                    Left resp -> putStrLn $ "Got response!: " ++ resp
                    Right err -> error err