com.fulcrologic.statecharts.convenience-macros — com.fulcrologic/statecharts 1.0.0-alpha11

ALPHA. NOT API STABLE.

This namespace includes functions and macros that emit statechart elements, but have a more concise notation for common cases that are normally a bit verbose.

Another purpose that is built into some of the macros is to make it more convenient to get clear diagram output when rendering the chart (TODO). The choice macro, for example, includes the conditional expressions as strigified notes on the nodes.

assign-on clj/s macro

(assign-on event location expression)

Creates a target-less transition that simply assigns the given expression to the data model at the given location when event happens. The expression MUST be symbolic. Use the convenience/assign-on function if don't want the expression macro-expanded as a string notation on the node.

Emits:

(transition {:event event}
  (assign {:location location :expr expression :diagram/expression "expression"}))

choice clj/s macro

(choice props & args)

Create a choice state. Notation is like cond, but :else is the only acceptable "default" predicate The pred should be the symbols that will resolve to functions that take [env data]. The target states may be raw keywords, or symbols that refer to the raw keyword, but MUST NOT be more complex expressions.

(choice {:id node-id ...}
  pred  target-state
  pred2 target-state2
  :else else-target-state)

is exactly equivalent to:

(state {:id node-id :diagram/prototype :choice}
  (transition {:cond pred :target target-state :diagram/condition "pred"})
  (transition {:cond pred2 :target target-state2 :diagram/condition "pred2"})
  (transition {:target else-target-state})

handle clj/s macro

(handle event expr)

A MACRO to generate a target-less transition with an expression (script node). Basically an event handler.

This is a macro. The event must be a symbol referencing a keyword or a keyword. The expr MUST be a symbol referring to a (fn [env data]). The result includes a diagram hint that can help with rendering the chart in a user-comprehensible form.

Emits:

(transition {:event event}
  (script {:expr expr :diagram/expression "expr"}))