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    @thi.ng/transducers-patch
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    0.4.7 • Public • Published

    transducers-patch

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    This project is part of the @thi.ng/umbrella monorepo.

    About

    Reducers for patch-based, immutable-by-default array & object editing. This is a support package for @thi.ng/transducers.

    The patchArray and patchObj reducers can be used in any reducer/transducer scenario and are useful for any form of declarative state update. By default all edits are performed non-destructively, but pushArray also supports in place editing (mutation).

    Status

    ALPHA - bleeding edge / work-in-progress

    Search or submit any issues for this package

    Installation

    yarn add @thi.ng/transducers-patch

    ES module import:

    <script type="module" src="https://cdn.skypack.dev/@thi.ng/transducers-patch"></script>

    Skypack documentation

    For Node.js REPL:

    # with flag only for < v16
    node --experimental-repl-await
    
    > const transducersPatch = await import("@thi.ng/transducers-patch");
    

    Package sizes (gzipped, pre-treeshake): ESM: 569 bytes

    Dependencies

    API

    Generated API docs

    TODO

    Basic usage

    import { patchArray, patchObj } from "@thi.ng/transducers-patch";
    import { reduce, reductions } from "@thi.ng/transducers";
    
    // flat array editing
    patchArray(
        // pass false to perform in-place edits (else immutable updates)
        false,
        // orig array to edit
        [1, 2, 3],
        // edits
        [
            // set idx #0 to 42
            ["set", 0, 42],
            // update idx #1 (here: times 10)
            ["update", 1, (x, n) => x * n, 10],
            // insert values @ idx #2
            ["insert", 2, [10, 11]],
            // delete (remove) idx #3
            ["delete", 3]
        ]
    );
    // [ 42, 20, 10, 3 ]
    
    // flat (immutable by default) array editing
    reduce(
        // reductions() used here to obtain step-wise edit results
        reductions(patchArray<number>()),
        // original array (wrapped here only for `reductions`)
        [[1, 2, 3]],
        [
            ["insert", 0, [10, 11]],
            ["update", 1, (x, n) => x * n, 10],
            ["delete", 3],
            ["set", 2, 200]
        ]
    );
    // [
    //     [1, 2, 3],
    //     [10, 11, 1, 2, 3],
    //     [10, 110, 1, 2, 3],
    //     [10, 110, 1, 3],
    //     [10, 110, 200, 3]
    // ]
    
    // nested (always immutable) object editing
    // (uses @thi.ng/paths for edits)
    reduce(
        reductions(patchObj()),
        [{ x: 23 }],
        [
            ["set", ["a", "b"], 1],
            ["update", ["a", "b"], (x, n) => x + n, 10],
            ["delete", ["x"]]
        ]
    ),
    // [
    //     { x: 23 },
    //     { x: 23, a: { b: 1 } },
    //     { x: 23, a: { b: 11 } },
    //     { a: { b: 11 } }
    // ]

    Stream-based processing

    .This example uses constructs from the @thi.ng/rstream package.

    import { stream, trace } from "@thi.ng/rstream";
    
    const initialState: any = { x: 23 };
    
    // create transformed stream mapping patch commands to states
    // since `patchArray` is only a reducer, we need to wrap it w/ the `scan` transducer
    // see: https://docs.thi.ng/umbrella/transducers/modules.html#scan
    export const state = stream<PatchObjOp>().transform(
        scan(patchObj(), initialState)
    );
    
    // add debug subscription
    state.subscribe(trace("state: "));
    
    state.next(["set", "a.b", 1]);
    // state: { x: 23, a: { b: 1 } }
    
    state.next(["update", ["a", "b"], (x, n)=> x + n, 10]);
    // state: { x: 23, a: { b: 11 } }
    
    state.next(["delete", "x"]);
    // state: { a: { b: 11 } }

    Authors

    Karsten Schmidt

    If this project contributes to an academic publication, please cite it as:

    @misc{thing-transducers-patch,
      title = "@thi.ng/transducers-patch",
      author = "Karsten Schmidt",
      note = "https://thi.ng/transducers-patch",
      year = 2020
    }

    License

    © 2020 - 2022 Karsten Schmidt // Apache Software License 2.0

    Install

    npm i @thi.ng/transducers-patch

    DownloadsWeekly Downloads

    164

    Version

    0.4.7

    License

    Apache-2.0

    Unpacked Size

    27.8 kB

    Total Files

    12

    Last publish

    Collaborators

    • thi.ng