feat: add fsm example

examples/go/fsm/README.md

@@ -0,0 +1,22 @@
+# FTL fsm example
+
+Run using:
+```sh
+> call fsm.sendEvent '{"id":"door3", "event":"open"}'
+debug:fsm:runner5: The door is open.
+
+> call fsm.sendEvent '{"id":"door3", "event":"jam"}'
+debug:fsm:runner5: The door is jammed. Fixing...
+
+> call fsm.sendEvent '{"id":"door3", "event":"unlock"}'
+debug:fsm:runner5: The door is unlocked.
+
+> call fsm.sendEvent '{"id":"door3", "event":"lock"}'
+debug:fsm:runner5: The door is locked.
+
+> call fsm.sendEvent '{"id":"door3", "event":"jam"}'
+debug:fsm:runner5: The door is jammed. Fixing...
+
+> call fsm.sendEvent '{"id":"door3", "event":"lock"}'
+error:fsm:runner5: Call to deployments dpl-fsm-7vye13artgx3hkx failed: call to verb fsm.sendEvent failed: failed to send fsm event: failed_precondition: no transition found from state fsm.openDoor for type fsm.Locked, candidates are unlockDoor, jamDoor
+```

examples/go/fsm/fsm.go

@@ -0,0 +1,82 @@
+package fsm
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/TBD54566975/ftl/go-runtime/ftl" // Import the FTL SDK.
+)
+
+type Opened struct{}
+type Unlocked struct{}
+type Locked struct{}
+type Jammed struct{}
+
+var door = ftl.FSM(
+	"door",
+	ftl.Start(OpenDoor),
+	ftl.Transition(OpenDoor, UnlockDoor),
+	ftl.Transition(OpenDoor, JamDoor),
+	ftl.Transition(UnlockDoor, OpenDoor),
+	ftl.Transition(UnlockDoor, LockDoor),
+	ftl.Transition(UnlockDoor, JamDoor),
+	ftl.Transition(LockDoor, UnlockDoor),
+	ftl.Transition(LockDoor, JamDoor),
+	ftl.Transition(JamDoor, OpenDoor),
+)
+
+//ftl:verb
+func OpenDoor(ctx context.Context, in Opened) error {
+	fmt.Println("The door is open.")
+	return nil
+}
+
+//ftl:verb
+func UnlockDoor(ctx context.Context, in Unlocked) error {
+	fmt.Println("The door is unlocked.")
+	return nil
+}
+
+//ftl:verb
+func LockDoor(ctx context.Context, in Locked) error {
+	fmt.Println("The door is locked.")
+	return nil
+}
+
+//ftl:verb
+func JamDoor(ctx context.Context, in Jammed) error {
+	fmt.Println("The door is jammed. Fixing...")
+	ftl.FSMNext(ctx, Opened{})
+	return nil
+}
+
+//ftl:enum
+type Event string
+
+const (
+	Open   Event = "open"
+	Unlock Event = "unlock"
+	Lock   Event = "lock"
+	Jam    Event = "jam"
+)
+
+type SendEventRequest struct {
+	ID    string
+	Event Event
+}
+
+//ftl:verb export
+func SendEvent(ctx context.Context, req SendEventRequest) error {
+	switch req.Event {
+	case Open:
+		return door.Send(ctx, req.ID, Opened{})
+	case Unlock:
+		return door.Send(ctx, req.ID, Unlocked{})
+	case Lock:
+		return door.Send(ctx, req.ID, Locked{})
+	case Jam:
+		return door.Send(ctx, req.ID, Jammed{})
+	default:
+		return fmt.Errorf("unknown event: %s", req.Event)
+	}
+}

examples/go/fsm/ftl.toml

@@ -0,0 +1,2 @@
+module = "fsm"
+language = "go"

examples/go/fsm/go.mod

@@ -0,0 +1,49 @@
+module ftl/fsm
+
+go 1.23.0
+
+replace github.com/TBD54566975/ftl => ../../..
+
+require github.com/TBD54566975/ftl v0.0.0-00010101000000-000000000000
+
+require (
+	connectrpc.com/connect v1.16.2 // indirect
+	connectrpc.com/grpcreflect v1.2.0 // indirect
+	connectrpc.com/otelconnect v0.7.1 // indirect
+	github.com/XSAM/otelsql v0.34.0 // indirect
+	github.com/alecthomas/atomic v0.1.0-alpha2 // indirect
+	github.com/alecthomas/concurrency v0.0.2 // indirect
+	github.com/alecthomas/participle/v2 v2.1.1 // indirect
+	github.com/alecthomas/types v0.16.0 // indirect
+	github.com/alessio/shellescape v1.4.2 // indirect
+	github.com/benbjohnson/clock v1.3.5 // indirect
+	github.com/danieljoos/wincred v1.2.0 // indirect
+	github.com/deckarep/golang-set/v2 v2.6.0 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/hashicorp/cronexpr v1.1.2 // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20240606120523-5a60cdf6a761 // indirect
+	github.com/jackc/pgx/v5 v5.7.1 // indirect
+	github.com/jackc/puddle/v2 v2.2.2 // indirect
+	github.com/jpillora/backoff v1.0.0 // indirect
+	github.com/kballard/go-shellquote v0.0.0-20180428030007-95032a82bc51 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/multiformats/go-base36 v0.2.0 // indirect
+	github.com/puzpuzpuz/xsync/v3 v3.4.0 // indirect
+	github.com/swaggest/jsonschema-go v0.3.72 // indirect
+	github.com/swaggest/refl v1.3.0 // indirect
+	github.com/zalando/go-keyring v0.2.5 // indirect
+	go.opentelemetry.io/otel v1.30.0 // indirect
+	go.opentelemetry.io/otel/metric v1.30.0 // indirect
+	go.opentelemetry.io/otel/trace v1.30.0 // indirect
+	golang.org/x/crypto v0.27.0 // indirect
+	golang.org/x/exp v0.0.0-20240909161429-701f63a606c0 // indirect
+	golang.org/x/mod v0.21.0 // indirect
+	golang.org/x/net v0.29.0 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.25.0 // indirect
+	golang.org/x/text v0.18.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+)