Getting started

[JeffreyBenjaminBrown]

Thanks for this repo! I can't wait to dig in.

It took me a day of work to get Greskell working. I'm hoping that by sharing this recipe I can save others some time. The problem is mostly not in Greskell; it's that there are a gazillion ways to use Gremlin. Eventually I struck on the following, which works:

• Start gremlin-server via Docker, as suggested in Tinkerpop's documentation, by running docker run --name gremlin -p 8182:8182 tinkerpop/gremlin-server:3.4.2 (if that's still the latest version). (I've added the -name and -p arguments; the first is optional, but the second is critical.)
• Clone Greskell.
• Add hspec to the build-depends list in greskell/greskell/greskell.cabal.
• Copy the submit to the Gremlin Server code from the README into a file called something like test-server.hs.
• Make two small changes to that code. First, add the line import Test.Hspec. Second, so that you can see whether it's actually working, add print statements to the case statement. For convenience, here's the result of those substitutions:

  
  import Control.Exception.Safe (bracket, try, SomeException)
  import Data.Foldable (toList)
  import Data.Greskell.Greskell (Greskell) -- from greskell package
  import Data.Greskell.Binder -- from greskell package
  (Binder, newBind, runBinder)
  import Network.Greskell.WebSocket -- from greskell-websocket package
  (connect, close, submit, slurpResults)
  import Test.Hspec

submitExample :: IO [Int] submitExample = bracket (connect "localhost" 8182) close $ \client -> do let (g, binding) = runBinder $ plusTen 50 result_handle <- submit client g (Just binding) fmap toList $ slurpResults result_handle

plusTen :: Int -> Binder (Greskell Int) plusTen x = do var_x <- newBind x return $ var_x + 10

main :: IO () main = hspec $ specify "submit" $ do egot <- try submitExample :: IO (Either SomeException [Int]) case egot of Left _ -> print "LEFT" >> return () -- probably there's no server running Right got -> print "RIGHT" >> (got shouldBe [60])

* From within the cloned repo, run `stack ghci`
* From within GHCI, run `:l test-server`, then run `main`.
* If it worked, it will print `RIGHT` to the screen. 
* If you stop the docker image that's running Gremlin Server, `main` should instead print `LEFT`.

If there's a more elegant solution, I'm all ears!

[debug-ito]

Thanks for reporting!

To run examples of README.md, just type stack test test-readme. You can directly modify README.md.

I'll revise the README.md to show that fact.

[debug-ito]

Updated README.md and "submit" example.