Module Js_of_ocaml_compiler.Pure_fun
val pure_expr : Js_of_ocaml_compiler.Code.Var.Set.t -> Code.expr -> boolval pure_instr : Js_of_ocaml_compiler.Code.Var.Set.t -> Code.instr -> boolval f : Code.program -> Js_of_ocaml_compiler.Code.Var.Set.t