CODEWITHSUNDEEP
elixir
tumbudu
tumbudu

Reputation: 831

(BadArityError) why its throwing error?

Simple elixir program to separate out odd and even numbers and then printing those.

iex(22)> c("testmap.ex") 
testmap.ex:1: warning: redefining module TestModule
[TestModule]

iex(23)> TestModule.test_map_reduce

** (BadArityError) #Function<0.56012634/2 in TestModule.pretty_print/1> with arity 2 called with 1 argument ({"even", [8, 6, 4, 2]})
    (elixir) lib/enum.ex:1047: anonymous fn/3 in Enum.map/2
    (stdlib) lists.erl:1262: :lists.foldl/3
    (elixir) lib/enum.ex:1047: Enum.map/2

Note in error it shows only one part of map, i.e

{"even", [8, 6, 4, 2]}

File:testmap.ex

defmodule TestModule do
    def test_map_reduce do
        list = [1,2,3,4,5,6,7,8,9]
        map = Enum.reduce list, %{}, fn(n, acc) ->
            key = getKey(n)
            case acc[key] do
                nil -> Map.put acc, key, [n]
                list -> Map.put acc, key, [n|list]
            end
        end
        pretty_print(map)
    end
    def getKey(n) do
        case rem n, 2 do
            0 -> "even"
            _ -> "odd"
        end
    end
    def pretty_print(number_map) do
        Enum.map number_map, fn(k, v) ->
            IO.inspect k
            IO.inspect v
        end
    end
end

Upvotes: 1

Views: 1406

Answers (1)

Gazler
Gazler

Reputation: 84140

You are passing 2 arguments to the anonymous function you pass to Enum.map/2 - the function should have an arity of 1.

Try this:

    Enum.map number_map, fn({k, v}) ->

{"even", [8, 6, 4, 2]} is a tuple of 2 elements.

Upvotes: 3

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