Orb

The rule is the program.

Declare the rules. Orb builds the app, or tells you why it can't.

curl -fsSL https://orb.almadar.io/install.sh | sh

Checkout

on Order · states: 3 · transitions: 3

Order { total }

PAY

(> @payload.amount 0)

SHIP

NEW_ORDER

nowpending

paid

shipped

An unpaid order cannot ship.

There is no SHIP out of pending.

Checkout

on Order · states: 3 · transitions: 4

emitsPAYemitsMOVED

INIT

PAY

(> @payload.amount 0)

SHIP

NEW_ORDER

nowpending

paid

shipped

The same file, running

Unpaid

checkout.lolololo

app std-orb-sample-checkout "1.0.0"
"std-orb-sample-checkout — the checkout program shown on orb.almadar.io's home page, running: an order that cannot ship before it is paid. The page shows this file as code beside the running trait, and each move is reported (MOVED) so its state machine can follow along."
orbital Orders {
  entity Order [runtime] {
    id : string!
    total : number
  }

  trait Checkout -> Order [interaction, instance] {
    initial: pending

    state pending {
      INIT -> pending
        (render-ui main { type: stack, gap: sm, children: [
          { type: typography, content: "Unpaid", variant: h4 },
          { type: button, label: "Pay 40", action: PAY, actionPayload: { amount: 40 } }
        ] })
      PAY -> paid when (> ?amount 0)
        (set @entity.total ?amount)
        (emit MOVED { event: "PAY" })
        (render-ui main { type: stack, gap: sm, children: [
          { type: typography, content: "Paid 40", variant: h4 },
          { type: button, label: "Ship", action: SHIP }
        ] })
    }

    state paid {
      SHIP -> shipped
        (emit MOVED { event: "SHIP" })
        (render-ui main { type: stack, gap: sm, children: [
          { type: typography, content: "Shipped", variant: h4 },
          { type: button, label: "New order", action: NEW_ORDER }
        ] })
    }

    state shipped {
      NEW_ORDER -> pending
        (emit MOVED { event: "NEW_ORDER" })
        (render-ui main { type: stack, gap: sm, children: [
          { type: typography, content: "Unpaid", variant: h4 },
          { type: button, label: "Pay 40", action: PAY, actionPayload: { amount: 40 } }
        ] })
    }

    emits {
      PAY {
        amount : number!
      }
      MOVED -> external {
        event : string!
      }
        @description "Each move names the event it took, so a diagram beside the order can follow it."
    }
  }

  page "/checkout" -> Checkout
}

Anything is a behavior.

Each one is a single .lolo file.

Orbital motion

STEP

TOGGLE_RUN

RESET

nowidle

Planets orbit a central mass under inverse-square gravity.

Running

Step 2

r=119.3px, v=2.25

Logic circuit

STEP

TOGGLE_RUN

RESET

nowidle

Logic gates combine inputs into outputs that follow their truth table.

Paused

Step 0

Circuit 1 — (A AND B) XOR (A OR B)

Output bulb = 0.

Galton board

STEP

TOGGLE_RUN

RESET

nowidle

Balls bounce off pegs and pile into a bell-shaped histogram.

Running

Step 2

0 ball(s) landed this step — bin 4 leads with 15 total

Every mistake gets a name and a line.

orb validate stops you with the code and the line.

orb validatebash

$ orb validate checkout.lolo
❌ [ORB_BINDING_PAYLOAD_FIELD_UNDECLARED] orbitals[0 (Orders)].traits[0 (Checkout)].stateMachine.transitions[1].guard[1]: Event 'PAY' uses @payload.amount (.lolo spelling: `?amount` or `@payload.amount`) but has no payload schema defined @ 16:27
   💡 declare the field in the event's `emits` payload block: `PAY -> external { amount : <type> }`
❌ [CIRCUIT_DEAD_END_STATE] orbitals[0 (Orders)].traits[0 (Checkout)].stateMachine.states: State 'shipped' has no outgoing transitions - it may be a dead end @ 10:3
   💡 Add outgoing transitions or mark as terminal state with isTerminal: true
Error: Schema validation failed with 2 error(s)