elm-xml-decode

XML decoder, sharing the spirit of Json.Decode. Ready for Elm 0.19.

Using jinjor/elm-xml-parser as its parser component, which is based on elm/parser.

Related Works

eeue56/elm-xml was an existing full-package XML parser/decoder for Elm, though I intended to provide an alternative XML decoder which exhibits following properties:

Provides Decoder-based APIs, sharing the spirit of Json.Decode
Also provides DSL-styled decoder compositions, sharing the sprits of Json.Decode.Pipeline
Handles list of XML node with identical tags, using ListDecoder type
Locates targeting XML nodes using "path" of tags, partially mimicking XPath

Examples

Basics:

import Xml.Decode exposing (..)

type alias Data =
    { string : String
    , integers : List Int
    }

dataDecoder : Decoder Data
dataDecoder =
    map2 Data
        (path [ "path", "to", "string", "value" ] (single string))
        (path [ "path", "to", "int", "values" ] (list int))

run dataDecoder
    """
    <root>
        <path>
            <to>
                <string>
                    <value>SomeString</value>
                </string>
                <int>
                    <values>1</values>
                    <values>2</values>
                </int>
            </to>
        </path>
    </root>
    """
--> Ok { string = "SomeString", integers = [ 1, 2 ] }

Pipeline Decoder compositions

We have map, map2 and variants, though the Pipeline style is also possible:

pipelineDecoder : Decoder Data
pipelineDecoder =
    succeed Data
        |> requiredPath [ "path", "to", "string", "value" ] (single string)
        |> requiredPath [ "path", "to", "int", "values" ] (list int)

Development

Globally install Elm Platform, elm-test, and elm-verify-examples

$ elm-test
$ elm-verify-examples
$ elm-verify-examples --elm-test=elm-test # Explicitly set elm-test to use, if particular elm-test version has some issues

Benchmark: Are they efficient? Are they fast?

Benchmark codes can be found in benchmarks/ directory. Using examples in W3School.

$ elm make Benchmarks.elm --optimize --output=../docs/index.html

Looking forward to see similar benchmarks from other related works!!

In Elm 0.19

Using elm-explorations/benchmark. Available here as a static web page.

It may hang for a while during JIT warming up, but keep waiting (~ a minute).

Sample result (on my desktop PC):

CPU: Core i7 8700K 3.7GHz
Mem: DDR4 32GB
Windows 10 (2019/01/13)
Google Chrome 71.0.3578.98 64bit

In Elm 0.18 (elm-xml-decode 1.x)

Using BrianHicks/elm-benchmark.

Sample result (on my MacBookPro early 2015):

CPU: Core i5 2.7GHz
Mem: DDR3 8GB 1867MHz
macOS (was El Capitan era, IIRC)
Google Chrome 63.0.3239.84 64bit

License

BSD-3-Clause

petteraas/elm-xml-decode