avoid relying on "Thm.definitionK" to pick up definitions -- this was an old hack related to locales (to avoid expanding locale constants to their low-level definition) that is no longer necessary
Arith = FOL +
classes arith < term
consts "0" :: "'a::arith" ("0")
"1" :: "'a::arith" ("1")
"+" :: "['a::arith,'a] => 'a" (infixl 60)
end