Extract answers from Functions module

lib/koans/05_functions.ex

@@ -6,12 +6,12 @@ defmodule Functions do
   end
   # A function starts with 'def', has a 'do-end' pair
   koan "it returns the last statement that was called" do
-    assert inside() == :light
+    assert inside() == :__
   end
 
   def quick_inline_product(a, b), do: a * b
   koan "Short functions can be defined in a single line, but mind the comman and colon!" do
-    assert quick_inline_product(2,3) == 6
+    assert quick_inline_product(2,:__) == 6
   end
 
   # A function can have an argument between parentheses, after the name
@@ -23,9 +23,12 @@ defmodule Functions do
     end
   end
 
-  koan "Can return different things" do
-    assert will_change(true) == :it_was_truthy
-    assert will_change(false) == "It really wasn't"
+  koan "Can return atoms..." do
+    assert will_change(true) == :__
+  end
+
+  koan "..or strings from the same function!" do
+    assert will_change(false) == :__
   end
 
   def repeat(times, message) do
@@ -33,64 +36,73 @@ defmodule Functions do
   end
 
   koan "Functions can have more than one arguement" do
-    assert repeat(3, "Hello ") == "Hello Hello Hello "
+    assert repeat(3, "Hello ") == :__
   end
 
-  def repeat_again(times \\ 3, message) do
+  def repeat_again(times \\ 5, message) do
     String.duplicate(message, times)
   end
 
   koan "But sometimes, you may want to default some arguments" do
-    assert repeat_again("Hello ") == "Hello Hello Hello "
+    assert repeat_again("Hello ") == :__
   end
 
   def first(foo, bar), do: "#{foo} and #{bar}"
   def first(foo), do: "only #{foo}"
-  koan "Functions are distinguished by name and arity - the number of arguments" do
-    assert first("One", "Two") == "One and Two"
-    assert first("One") == "only One"
+  koan "functions with the same name are distinguished by arity" do
+    assert first("One", "Two") == :__
   end
+  koan "the name stays - the number of arguments varies" do
+    assert first("One") == :__
+  end
+
 
   def sum_up(thing) when is_list(thing), do: :entire_list
   def sum_up(_thing), do: :single_thing
-  koan "You can 'guard' functions against their arguments" do
-    assert sum_up([1,2,3]) == :entire_list
-    assert sum_up(1) == :single_thing
+  koan "You can 'guard' functions from their arguments" do
+    assert sum_up([1,2,3]) == :__
+  end
+  koan "no guard means just that - anything" do
+    assert sum_up(1) == :__
   end
 
   def bigger(a,b) when a >  b, do: "#{a} is bigger than #{b}"
   def bigger(a,b) when a <= b, do: "#{a} is not bigger than #{b}"
-  koan "You can also create intricate guards based on the values" do
-    assert bigger(10, 5) == "10 is bigger than 5"
-    assert bigger(4, 27) == "4 is not bigger than 27"
+  koan "You can also create intricate guards based on the values..." do
+    assert bigger(10, 5) == :__
+  end
+  koan "...to make the body of the function clearer" do
+    assert bigger(4, 27) == :__
   end
 
   def the_length(0), do: "It was zero"
   def the_length(number), do: "The length was #{number}"
   koan "You can also 'guard' with concrete values" do
-    assert the_length(0) == "It was zero"
-    assert the_length(5) == "The length was 5"
+    assert the_length(0) == :__
+  end
+  koan "Or just let the argument roll" do
+    assert the_length(5) == :__
   end
 
   koan "You can also define inline functions and call them with .()" do
     multiply = fn (a,b) -> a * b end
-    assert multiply.(2,3) == 6
+    assert multiply.(2,3) == :__
   end
 
   koan "You can even go shorter, by using &(..) and positional arguments" do
     multiply = &(&1 * &2)
-    assert multiply.(2,3) == 6
+    assert multiply.(2,3) == :__
   end
 
   def two_arguments(_first, second), do: second
   koan "You can also show that certain arguments are ignored in the body by adding an underscore" do
-    assert two_arguments(:hi_there, "the other one") == "the other one"
+    assert two_arguments(:hi_there, "the other one") == :__
   end
 
   def multiply_then_call(number, fun), do: fun.(number*5)
   def square(number), do: number * number
   koan "You can 'capture' functions if you want to pass them around as values" do
-    assert multiply_then_call(2, &square/1) == 100
+    assert multiply_then_call(2, &square/1) == :__
   end
 
   koan "functions can be combined elegantly with the pipe operator" do
@@ -99,6 +111,6 @@ defmodule Functions do
     |> Enum.map(&(String.capitalize(&1)))
     |> Enum.join(" ")
 
-    assert result == "Full Name"
+    assert result == :__
   end
 end