Benchmark of pattern matching vs. List.indexedMap

BenchmarkPattern.elm

module BenchmarkPattern exposing (main)

import Benchmark exposing (..)
import Benchmark.Runner exposing (BenchmarkProgram, program)


main : BenchmarkProgram
main =
    program suite


suite : Benchmark
suite =
    let
        sampleList : List Int
        sampleList =
            List.range 0 100
                |> List.map (\item -> ( item, List.range 0 10 ))

        addOne : Int -> Int
        addOne =
            (+) 1

        addOneExceptForFirstPatternMatch : List Int -> List Int
        addOneExceptForFirstPatternMatch list =
            case list of
                [] ->
                    []

                head :: tail ->
                    head :: List.map addOne tail

        patternMatch : List ( Int, List Int ) -> List ( Int, List Int )
        patternMatch list =
            case list of
                [] ->
                    []

                head :: tail ->
                    Tuple.mapSecond addOneExceptForFirstPatternMatch head :: List.map (Tuple.mapSecond (List.map addOne)) tail

        addOneExceptForFirstIndexedMap : List Int -> List Int
        addOneExceptForFirstIndexedMap =
            List.indexedMap
                (\i item ->
                    if i == 0 then
                        item

                    else
                        addOne item
                )

        indexedMap : List ( Int, List Int ) -> List ( Int, List Int )
        indexedMap =
            List.indexedMap
                (\i tuple ->
                    if i == 0 then
                        Tuple.mapSecond addOneExceptForFirstIndexedMap tuple

                    else
                        Tuple.mapSecond (List.map addOne) tuple
                )
    in
    describe ""
        [ -- nest as many descriptions as you like
          Benchmark.compare "Pattern matching vs. indexedMap"
            "Pattern Match"
            (\_ -> patternMatch sampleList)
            "indexedMap"
            (\_ -> indexedMap sampleList)
        ]

results.md

Benchmark Report

pattern matching vs. indexedMap

name	runs / second	% change	goodness of fit
Pattern Match	12,168	-	99.74%
indexedMap	12,284	+0.95%	99.86%