Cheat sheet

The core of arche-lang on one page: the declarations every model is written with (the core set of the language), one line each. The ideas behind them are in concepts; every property is in the language reference.

Declarations#

Write	What it is
`project Pump "Water pump" { version "0.1" }`	The project: its name, version, the libraries it uses. One per model.
`include "parts/motor.arche"`	Another file of the model.
`type Flow = float32 unit l/min range 0..120`	A data type: a base type, a unit, a range.
`enum Mode { Off, On }`	A choice of named values.
`struct Point { x: float32; y: float32 }`	A record of fields.
`const MAX_FLOW = 100 unit l/min`	A named value.
`message PRESS "Press" { count: uint8 }`	What travels between parts (or `message GO: bool`, one value).
`component Lamp "Lamp" { … }`	A definition: its ports, variables, functions, states.
`in cmd: can receives PRESS`	A port that receives. `out click: can sends PRESS` sends; `inout` does both.
`var level: uint8 = 0`	A variable of the component, with its first value.
fn dim "Dim" ```arche … ```	A function and what it does, in the action language. `main` runs from the start.
`states { state Off; state On; Off -> On on PRESS [level > 0] }`	The state machine: the first state is where it starts; `A -> B on trigger [guard] / action`.
`system Room "Room" { … }`	What Arche shows and runs: parts and the links between them.
`part lamp: Lamp`	An instance of a component, in a system.
`button.click -> lamp.cmd { latency 1ms }`	A link from a port to a port.
`requirement REQ-ON "Turn on" { text "The lamp shall …" }`	What must hold. `verified-by TP-ON` names its test.
`trace satisfies Room.lamp -> REQ-ON`	A trace written apart (or `satisfies REQ-ON` in the component).
`test-plan TP-ON "Turning on" { case TC-1 "…" { … } }`	Tests, run in the simulator: `at 0ms do …`, `within 50ms expect …`.

In a ```arche body#

Write	What it does
`var d = speed * 2.0`	A local variable.
`level = 0`, `level += 1`	Sets a variable of the part.
`if level > 0 { … } else { … }`	A choice. `while c { … }`, `for i in 0..4 { … }` loop.
`send click PRESS { count: 1 }`	Sends a message on a port.
`goto On`, `state == On`	Changes the state; tests it.
`wait 10ms`	Waits.
`dim()`, `return x`	Calls a function of the part; returns.
`log "pressed", level`	Writes to the simulator's log.

A body written in ```python still works: the quick fix Convert to arche body (or archec fix --only arche-body) rewrites a simple one.

Commands#

Run	To
`archec new`	Start a project from a template.
`archec check main.arche`	Check the model.
`archec sim main.arche`	See it run in the browser.
`archec test main.arche`	Run its test plans in the simulator.
`archec gen main.arche --target c`	Generate code (`embassy`, `go`, `ros2`…).
`archec build main.arche`	Write the Arche project, to open in Arche.

All of it at once#

project Room "Room" {
  version "0.1"
}

message PRESS "Press" { count: uint8 }

const MAX_LEVEL = 10

requirement REQ-ON "Turn on" {
  text "The lamp shall turn on within 50 ms of a press."
  verified-by TP-ON
}

component Button "Button" {
  out click: can sends PRESS
}

component Lamp "Lamp" {
  satisfies REQ-ON
  in cmd: can receives PRESS
  var level: uint8 = 0
  states {
    state Off
    state On
    Off -> On on PRESS
    On -> Off on PRESS
  }
  fn main "Brighten" ```arche
    while true {
      wait 100ms
      if state == On and level < MAX_LEVEL {
        level += 1
      }
    }

}

system Home "Home" { part button: Button part lamp: Lamp button.click -> lamp.cmd }

test-plan TP-ON "Turning on" { case TC-ON-01 "A press turns it on" { verifies REQ-ON at 0ms do send(button.click, PRESS(count=1)) within 50ms expect lamp.state == "On" } }