diff --git a/lib/koans/10_enums.ex b/lib/koans/10_enums.ex index 0a0a380..67c295d 100644 --- a/lib/koans/10_enums.ex +++ b/lib/koans/10_enums.ex @@ -13,24 +13,26 @@ defmodule Enums do assert Enum.count([a: 77, b: 23, c: 12, d: 33, e: 90, f: 113]) == :__ end + def less_than_five(n), do: n < 5 koan "Elements can have a lot in common" do - less_than_five = &(&1 <=5) - assert Enum.all?([1,2,3], less_than_five) == :__ + assert Enum.all?([1,2,3], &less_than_five/1) == :__ end + def less_than_two(n), do: n < 2 koan "If one if different, all elements are not alike" do - less_than_two = &(&1 <=2) - assert Enum.all?([1, 2, 3, 2], less_than_two) == :__ + assert Enum.all?([1, 2, 3, 2], &less_than_two/1) == :__ end + def is_even?(n), do: rem(n, 2) == 0 + koan "sometimes you you just want to know if there are any elements fullfilling a condition" do - is_even? = &(rem(&1, 2) == 0) - assert Enum.any?([1,2,3], is_even?) == :__ + assert Enum.any?([1,2,3], &is_even?/1) == :__ end + def divisible_by_five(n), do: rem(n, 5) == 0 + koan "if not a single element fits the bill, any? returns false" do - divisible_by_five = &(rem(&1, 5) == 0) - assert Enum.any?([1,2,3], divisible_by_five) == :__ + assert Enum.any?([1,2,3], &divisible_by_five/1) == :__ end koan "Sometimes you just want to know if an element is part of the party" do @@ -41,30 +43,31 @@ defmodule Enums do assert Enum.member?([1,2,3], 30) == :__ end + def multiply_by_ten(n), do: 10 * n + koan "map converts each element of a list by running some function with it" do - multiply_by_ten = &(&1 * 10) - assert Enum.map([1,2,3], multiply_by_ten) == :__ + assert Enum.map([1,2,3], &multiply_by_ten/1) == :__ end koan "You can even return a list with entirely different types" do - is_even? = &(rem(&1,2) == 0) - assert Enum.map([1,2,3], is_even?) == :__ + assert Enum.map([1,2,3], &is_even?/1) == :__ end + koan "But keep in mind that the original list remains unchanged" do input = [1,2,3,4] - assert Enum.map(input, fn element -> rem(element, 2) == 0 end) == :__ + assert Enum.map(input, &is_even?/1) == :__ assert input == :__ end + def is_odd?(n), do: rem(n, 2) == 1 + koan "Filter allows you to only keep what you really care about" do - is_odd? = &(rem(&1, 2) == 1) - assert Enum.filter([1,2,3], is_odd?) == :__ + assert Enum.filter([1,2,3], &is_odd?/1) == :__ end koan "Reject will help you throw out unwanted cruft" do - is_odd? = &(rem(&1, 2) == 1) - assert Enum.reject([1,2,3], is_odd?) == :__ + assert Enum.reject([1,2,3], &is_odd?/1) == :__ end koan "You three there, follow me!" do @@ -75,18 +78,18 @@ defmodule Enums do assert Enum.take([1,2,3,4,5], 10) == :__ end + def less_than_four(n), do: n < 4 koan "Take what you can..." do - less_than_four = &(&1 < 4) - assert Enum.take_while([1,2,3,4,5,6,7], less_than_four) == :__ + assert Enum.take_while([1,2,3,4,5,6,7], &less_than_four/1) == :__ end koan "Just like taking, you can also drop elements" do assert Enum.drop([-1,0,1,2,3], 2) == :__ end + def negative?(n), do: n < 0 koan "Drop elements until you are happy" do - negative = &(&1 <= 0) - assert Enum.drop_while([-1,0,1,2,3], negative) == :__ + assert Enum.drop_while([-1,0,1,2,3], &negative?/1) == :__ end koan "Forming groups makes uns stronger" do @@ -97,7 +100,6 @@ defmodule Enums do koan "You get as many groups as you can have different results" do assert Enum.group_by([1,2,3,4,5,6], fn element -> rem(element, 3) end) == :__ - end koan "Zip-up in pairs!" do @@ -113,15 +115,15 @@ defmodule Enums do end koan "When you want to find that one pesky element" do - assert Enum.find([1,2,3], fn element -> rem(element,2) == 0 end) == :__ + assert Enum.find([1,2,3], &is_even?/1) == :__ end koan "...but you don't quite find it..." do - assert Enum.find([1,2,3], fn element -> rem(element,5) == 0 end) == :__ + assert Enum.find([1,2,3], &divisible_by_five/1) == :__ end koan "...you can settle for a consolation prize" do - assert Enum.find([1,2,3], :no_such_element, fn element -> rem(element,5) == 0 end) == :__ + assert Enum.find([1,2,3], :no_such_element, &divisible_by_five/1) == :__ end koan "Collapse an entire list of elements down to a single one by repeating a function." do diff --git a/test/koans_harness_test.exs b/test/koans_harness_test.exs index 048aae7..3615802 100644 --- a/test/koans_harness_test.exs +++ b/test/koans_harness_test.exs @@ -182,7 +182,7 @@ defmodule KoansHarnessTest do [1,2,3,4,5], [1,2,3], [1,2,3], - [1,2,3], + [0,1,2,3], %{ :odd => [3,1], :even => [4,2] }, %{ 0 => [6, 3], 1 => [4, 1], 2 => [5, 2]}, [{1, :a}, {2, :b}, {3, :c}],