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This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2023 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Design pattern: Threading State

Description: Definite Clause Grammars (DCGs) can be used to thread state whenever we have a sequence of calls where each call takes an input state and an output state as arguments with the output state of each call being passed to the next call as its input state. DCGs notation allows abstracting the state arguments and thus simplifying the code.

The sample implementation converts a floating-point number into an integer number using a sequence of operations represented using Definite Clause Grammar rules.