Def.Xval size_ty : size Costlang.Ty.tRuntime type for size
val true_ : bool reprval false_ : bool reprval free : name:Free_variable.t -> size reprval lam' :
name:string ->
'a Costlang.Ty.t ->
('a repr -> 'b repr) ->
('a -> 'b) reprInstantiation of lam' for size repr argument