version 1 .

ConstructorSpec = <rec any int> / <arr int> / <dict>.

Pattern = </[
  <_>
  <bind symbol Pattern>
  <and [Pattern ...]>
  <not Pattern>
  <lit any>
  <compound ConstructorSpec { any: Pattern ...:... }>
]>.

Template = </[
  <ref symbol>
  <lit any>
  <compound ConstructorSpec { any: Template ...:... }>
]>.

Rewrite = <rewrite Pattern Template>.