Bonsai.Types

data BONSAI :: Effect

Effect for public types

type BrowserEvent msg = F msg

A BrowserEvent is simply a decoded foreign

This is inherently composable - it's a full monad.

data Cmd eff msg

A Command represents messages that should be applied to the Bonsai model

A command is either Pure (the constructor Cmd) or an asynchronous Task. The pure command simply contains the messages that will be emitted. The asynchronous Task gets an emitter function that it can use to emit messages at will.

There is currently no effectful synchronous command - there used to be, but it did not turn out very useful except in dumbed down examples.

There could be a helper function that expresses simple effectful commands as Tasks though.

There used to be a helper type for TaskContext -> Aff but for some reason it did not unify in user code. So the recommendation is to produce the command, not the function with complicated signature that goes inside a TaskCmd.

Constructors

• Cmd (Array msg)
• TaskCmd (TaskContext eff msg -> Aff eff Unit)

Instances

• Functor (Cmd eff)

type CmdDecoder aff msg = Foreign -> Either Error (Cmd aff msg)

And finally, a Command Decoder turns a foreign into a command

The CmdDecoder will be implemented using EventDecoders internally.

newtype Document

The type for the global javascript document

Constructors

• Document Foreign

type Emitter aff msg = Either Error (Cmd aff msg) -> Eff aff Boolean

Emitters will get the Cmd into the Bonsai event loop.

The javascript side has little knowlege about the internal structure of the purescript types, so an emitting function is provided that takes care of all that.

On error, the emitter returns true to signal to javascript that the originating event should be logged to the console.

type EventDecoder msg = Foreign -> BrowserEvent msg

A EventDecoder decodes a foreign to a BrowserEvent

type TaskContext eff msg = { document :: Document, emitter :: msg -> Eff eff Unit, fiber :: AVar (Fiber eff Unit) }

The Task Context holds the emitter function for the task

Maybe: a way to get at the current model? That would mean the model has to encoded in all the view functions as well. Maybe not a good idea.

newtype Window

The type for the global javascript window

Constructors

• Window Foreign

f2cmd :: forall eff b a. (a -> Cmd eff b) -> F a -> Either Error (Cmd eff b)

Helper to turn an F into emittable (Either Error Cmd)

emptyCommand :: forall msg aff. Cmd aff msg

Produces an empty command.

pureCommand :: forall msg aff. msg -> Cmd aff msg

Produces a pure command