Use bool for predicates

[bettio]

Signed-off-by: Davide Bettio [email protected]

These changes are made under both the "Apache 2.0" and the "GNU Lesser General Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

[pguyot]

Also term_is_number (can't comment on the line)

[bettio]

This changes make sense from a theoretical point of view, from an empirical point of view they might slow down the generated binary.