elm-xml-decode

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

Using miniBill/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

Install reasonably new Node.js (currently Node.js 22 is tested)

npm install
npm test

Benchmarks

Benchmark app can be found in benchmarks/ directory. Using examples in W3School and elm-explorations/benchmark.

npm run generate-benchmark
# Open docs/index.html

Also available at https://ymtszw.github.io/elm-xml-decode/

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

Elm 0.19.1, elm-xml-decode 3.2.1

Sample result (on my Windows 10 machine):

• Environment
  • CPU: Intel Core i7-8700K @ 3.7GHz
  • Mem: 64GB
  • Windows 10 Pro, 10.0.19044
  • Google Chrome 98.0.4758.82 64bit
• Versions
  • elm 0.19.1
  • elm-xml-decode version: 3.2.1
  • elm-benchmark 1.0.2

License

BSD-3-Clause