Implement run command for the web service

[TristanCacqueray]

Is your feature request related to a problem? Please describe.
When playing with a text editor, it is not convenient to use the REPL to load new definitions.

Describe the solution you'd like
I would like to load swarm code using the web service directly from my text editor.
The editor integration could provide a send-buffer or something equivalent to automate that process.

[xsebek]

That sounds cool! Should this only accept definitions or also scripts?

I can imagine wanting to restart the scenario when writing a script to solve a maze, but only loading new definitions when playing the long game. 🤔

[byorgey]

In swarm-lang there is no difference between definitions and scripts; a sequence of definitions is a script. I don't think there's any reasonable way to restrict something to only accept definitions.

[xsebek]

@byorgey I was thinking that we could easily restrict that if you for example wanted to reload as you type, but not run any commands.

But that might not be a problem or could be offered as a config option later.

[xsebek]

@TristanCacqueray how would this work on the application state though?

The current Web API only has access to GameState, would this be a Post '[Text] () type of endpoint where the text is parsed as Term and run by the base robot?

The alternative I see is adding some generic channel to the Web service, through which it would pass a Term and receive the Value once that term has finished executing. In the current brick application, we could route this through an event, so that it can be added to the UIState REPL history. But in principle, we could cut the brick part and run Swarm on a server, with the run term being executed in the base robot directly.

Honestly, I am really intimidated by the Servant types, so if you could add at least a minimal scaffolding for one POST method with error handling, that would make it much easier. 😉

[TristanCacqueray]

@xsebek I don't know how exactly how the text term would be submitted to the game state, but from the API perspective, the handler would look like this:

type SwarmAPI =
  ... 
  :<|> "run" :> ReqBody '[JSON] Text :> Post '[JSON] Text

runHandler userSuppliedCommand = do
  term <- parse userSuppliedCommand
  eval term
  pure "completed"

• ReqBody '[JSON] Text indicates that the request will have a body of type application/json containing a text.
• Post '[JSON] Text indicate the path returns a text encoded in json.

The user would use the handler with curl -XPOST -d'"the program"' -H 'Content-Type: application/json' localhost/run