nominal compiler_v1 = ()
nominal compiler_v2 = ()
nominal source_main = ()

union compilation compiler source result =
    | CompileV1 :: compilation compiler_v1 source_main string
    | CompileV2 :: compilation compiler_v2 source_main string

union cache_key compiler source result =
    | KeyV1 :: string -> cache_key compiler_v1 source_main string
    | KeyV2 :: string -> cache_key compiler_v2 source_main string

inl restore forall compiler source result.
    (compilation : compilation compiler source result)
    (key : cache_key compiler source result)
    : result =
    match compilation, key with
    | CompileV1, KeyV1 _ => "cache-v1"
    | CompileV2, KeyV2 _ => "versioned-cache-key"

inl main () : string =
    restore CompileV2 (KeyV2 "sha256:main")