Most formal "specs" (the part that defines the system's actual behavior) are just code. So a formally verified (or compiled) spec is really just a different programming language, or something layered on top of existing code. Like TypeScript types are a non-formal but empirical verification layer on top of JavaScript.
The hard part remains: translating from human-communicated requirements to a maintainable spec (formally verified or not) that completely defines the module's behavior.
Most formal "specs" (the part that defines the system's actual behavior) are just code. So a formally verified (or compiled) spec is really just a different programming language, or something layered on top of existing code. Like TypeScript types are a non-formal but empirical verification layer on top of JavaScript.
The hard part remains: translating from human-communicated requirements to a maintainable spec (formally verified or not) that completely defines the module's behavior.