feat: registry, normalorder engine, lambda codec and marshaler

pkg/engine/normalorder/engine.go

@@ -0,0 +1,34 @@
+package normalorder
+
+import (
+	"git.maximhutz.com/max/lambda/pkg/engine"
+	"git.maximhutz.com/max/lambda/pkg/lambda"
+)
+
+type Engine struct {
+	expr lambda.Expression
+}
+
+func (e Engine) Get() (lambda.Expression, error) {
+	return e.expr, nil
+}
+
+func (e Engine) Set(l lambda.Expression) error {
+	e.expr = l
+	return nil
+}
+
+func (e Engine) Step(i int) bool {
+	var reduced bool
+
+	for range i {
+		e.expr, reduced = ReduceOnce(e.expr)
+		if !reduced {
+			return false
+		}
+	}
+
+	return true
+}
+
+var _ engine.Engine[lambda.Expression] = (*Engine)(nil)