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-- Copyright (c) 2022-2023 Chris Pressey, Cat's Eye Technologies
-- This work is distributed under an MIT license.  See LICENSES directory:
-- SPDX-License-Identifier: LicenseRef-MIT-X-Parc

module ParcMerge (ok, fail, pred, update, seq, alt, many, merge, ParseState(Parsing, Failure)) where

import Prelude hiding (fail, pred, seq)
import ParcSt2St

merge :: (ParseState a -> ParseState b) -> (a -> b -> c) -> ParseState a -> ParseState c
merge c f =
    (\st ->
        case st of
            Failure -> Failure
            Parsing s0 v0 ->
                case c st of
                    Failure -> Failure
                    Parsing s v1 -> Parsing s (f v0 v1))