added worker_group;
fork: default to subgroup of worker_group;
removed obsolete fork_local;
join/get_result: cumulative flattened exceptions;
map: subgroup of worker_group;
structure Nat =
struct
datatype nat = Suc of nat | Zero_nat;
fun less_nat m (Suc n) = less_eq_nat m n
| less_nat n Zero_nat = false
and less_eq_nat (Suc m) n = less_nat m n
| less_eq_nat Zero_nat n = true;
end; (*struct Nat*)
structure Codegen =
struct
fun in_interval (k, l) n =
(Nat.less_eq_nat k n) andalso (Nat.less_eq_nat n l);
end; (*struct Codegen*)