tebello-thejane / bitx.hs

(Hopefully useful) Haskell bindings to the BitX bitcoin exchange's API.

(Hopefully useful) Haskell bindings to the Luno (formerly BitX) cryptocurrency exchange's API.

As a minimal example, to get the current selling price (in South African Rand) of Bitcoin on the Luno exchange, do the following:

import Control.Lens ((^.))
import Network.Bitcoin.BitX (BitXAPIResponse(..), getTicker, CcyPair(..))
import qualified Network.Bitcoin.BitX as BitX
import Data.Text (unpack)
import Network.HTTP.Types.Status (Status(..))
import Network.HTTP.Client (responseStatus)

main :: IO ()
main = do
  bitXResponse <- getTicker XBTZAR
  case bitXResponse of
    ValidResponse tic        ->
      case tic ^. BitX.ask of
        Nothing              ->  putStrLn "The BTC-ZAR exchange not currently have an ask price..."
        Just p               ->  putStrLn ("1 Bitcoin will set you back ZAR" ++ show p ++ ".")
    ErrorResponse err        ->
        error $ "BitX error received: \"" ++ unpack (err ^. BitX.error) ++ "\""
    ExceptionResponse ex     ->
        error $ "Exception was thrown: \"" ++ show ex ++ "\""
    UnparseableResponse _ resp ->
        error $ "Bad HTTP response; HTTP status code was: \"" ++ (show . statusCode . responseStatus $ resp) ++ "\""

Note that the code snippet above depends on http-types, text, http-client, lens (or any lens-compatible package, such as microlens), and finally bitx-bitcoin.

This library is known to work on Windows, but if you wish to use it then you will have to do a bit more work due to the Network library not building on Windows out of the box. Your best bet might be to just use Stack.

bitx.hs's Issues

Precision issue

λ> B.postEncode $ B.OrderRequest B.XRPXBT B.BID 673 0.00002683
[("pair","XRPXBT"),("type","BID"),("volume","673"),("price","0.000026")]

Not sure where we're losing precision but this is clearly wrong!

Could not find module ‘Network’

src/Network/Bitcoin/BitX/Internal.hs:26:1: error:
    Could not find module ‘Network’
    Use -v to see a list of the files searched for.
   |
26 | import Network (withSocketsDo)

Ticker values need to be `Scientific`

Currently these are Int, which is fine for XBTZAR since no decimals are allowed in the price, but useless for ETHXBT since the prices are always fractional in this market.

bitx-bitcoin-0.2.0.0 does not compile

Citing from http://hydra.cryp.to/build/926883/nixlog/1/raw:

src/Network/Bitcoin/BitX/Internal.hs:25:8:
    Could not find module ‘Record.Lens’
    Use -v to see a list of the files searched for.

Streaming API

I have some code implementing the streaming websocket API which I'd like to contribute, but it probably needs some more cleaning up. Also I used type-level symbols for pairs rather than value-level constants, so the API will probably need to be changed. Filing this so I hopefully don't forget forever.

Creating managers is expensive

Currently a new connection manager is created for every request. This is fairly expensive, mainly because for TLS all of the certificates in the certificate store need to be parsed and loaded. If I replace globalManager with this, my CPU usage goes down a lot:

{-# NOINLINE yuck #-}
yuck :: NetCon.Manager
yuck = unsafePerformIO (NetCon.newManager NetCon.tlsManagerSettings)

globalManager :: IO NetCon.Manager
globalManager = pure yuck

(Obviously this isn't a great thing to do, it's just a quick'n'dirty PoC of sharing the manager)

What we probably want is some way to pass a manager in to the operation to be used, but I'm not quite sure how to do this without creating duplicate variants of every operation in the API, which sounds tedious.

Stackage nightly test failure

Failures:
  test/Network/Bitcoin/BitX/Spec/Specs/NetSpec.hs:24: 
  1) Network.Bitcoin.BitX.Spec.Specs.Net, 
       Public BitX connectivity, 
       getTrades connects to BitX and works

CI is totally buggered

We have basically given up on Travis-CI as it has a lot of noisy failures.

• Are we trying to support too many GHC versions?
• And what about the jobs which just decide to fail on whim?

Get this shit stable and fixed, so that we don't ignore valid failures due to all this noise.

ETHXBT pair

Luno recently added this (along with the ETH asset). Should be a pretty easy change, I'll try send a PR shortly.

Travis jobs randomly run into 503 issues

The travis jobs randomly time out when testing live API connectivity. This might be due to the default (non-container-based) infrastructure sharing the same IP address between multiple instances running the same test, and thus flooding BitX.

Perhaps moving to container-based infrastructure might help.

Parsing empty trades response fails

If you request trade information where no trades match, the Luno API returns null instead of an empty array, causing a parse failure.