Initial commit

elixir/freelancer-rates/.exercism/config.json

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+{
+  "authors": [
+    "angelikatyborska"
+  ],
+  "contributors": [
+    "neenjaw"
+  ],
+  "files": {
+    "solution": [
+      "lib/freelancer_rates.ex"
+    ],
+    "test": [
+      "test/freelancer_rates_test.exs"
+    ],
+    "exemplar": [
+      ".meta/exemplar.ex"
+    ]
+  },
+  "language_versions": ">=1.10",
+  "forked_from": [
+    "javascript/freelancer-rates"
+  ],
+  "blurb": "Learn about integers and floating point numbers by helping a freelancer communicate with a project manager about billing."
+}

elixir/freelancer-rates/.exercism/metadata.json

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+{"track":"elixir","exercise":"freelancer-rates","id":"25db5ef05b9b40a09965866b08a13f3f","url":"https://exercism.org/tracks/elixir/exercises/freelancer-rates","handle":"negrienko","is_requester":true,"auto_approve":false}

elixir/freelancer-rates/.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

elixir/freelancer-rates/.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+numbers-*.tar
+

elixir/freelancer-rates/HELP.md

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+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be skipped.
+
+Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
+
+For example:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/freelancer_rates.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- The [Elixir track's programming category on the forum](https://forum.exercism.org/c/programming/elixir)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.

elixir/freelancer-rates/HINTS.md

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+# Hints
+
+## General
+
+- Read about basic arithmetic in the official [Getting Started guide][getting-started-basic-arithmetic].
+- Browse the [`Float`][float-functions] and [`Kernel`][kernel-arithmetic-operators] modules to learn about functions and operators that work with floats.
+
+## 1. Calculate the daily rate given an hourly rate
+
+- [Basic arithmetic operations][kernel-arithmetic-operators] where one argument is an integer, and the other is a float, will return a float.
+
+## 2. Calculate a discounted price
+
+- [Basic arithmetic operations][kernel-arithmetic-operators] where one argument is an integer, and the other is a float, will return a float.
+
+## 3. Calculate the monthly rate, given an hourly rate and a discount
+
+- There is a [built-in function][kernel-trunc] for changing floats to integers.
+- There is a [built-in function][float-ceil] for rounding floats up.
+
+## 4. Calculate the number of workdays given a budget, hourly rate and discount
+
+- There is a [built-in function][float-floor] for rounding floats down with desired precision.
+
+[getting-started-basic-arithmetic]: https://elixir-lang.org/getting-started/basic-types.html#basic-arithmetic
+[kernel-arithmetic-operators]: https://hexdocs.pm/elixir/Kernel.html#*/2
+[kernel-trunc]: https://hexdocs.pm/elixir/Kernel.html#trunc/1
+[float-functions]: https://hexdocs.pm/elixir/Float.html#functions
+[float-ceil]: https://hexdocs.pm/elixir/Float.html#ceil/2
+[float-floor]: https://hexdocs.pm/elixir/Float.html#floor/2

elixir/freelancer-rates/README.md

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+# Freelancer Rates
+
+Welcome to Freelancer Rates on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
+
+## Introduction
+
+## Integers
+
+There are two different kinds of numbers in Elixir - integers and floats.
+
+Integers are whole numbers.
+
+```elixir
+integer = 3
+# => 3
+```
+
+## Floating Point Numbers
+
+Floats are numbers with one or more digits behind the decimal separator. They use the 64-bit double precision floating-point format.
+
+```elixir
+float = 3.45
+# => 3.45
+```
+
+### Working with numbers
+
+In the [`Integer`][integer-functions] and [`Float`][float-functions] modules you can find some useful functions for working with those types. Basic arithmetic operators are defined in the [`Kernel`][kernel-arithmetic-operators] module.
+
+### Conversion
+
+Integers and floats can be mixed together in a single arithmetic expression. Using a float in an expression ensures the result will be a float too.
+
+```elixir
+2 * 3
+# => 6
+
+2 * 3.0
+# => 6.0
+```
+
+However, when doing division, the result will always be a float, even if only integers are used.
+
+```elixir
+6 / 2
+# => 3.0
+```
+
+To convert a float to an integer, you can discard the decimal part with [`trunc/1`][trunc-1].
+
+[integer-functions]: https://hexdocs.pm/elixir/Integer.html#functions
+[float-functions]: https://hexdocs.pm/elixir/Float.html#functions
+[kernel-arithmetic-operators]: https://hexdocs.pm/elixir/Kernel.html#*/2
+[trunc-1]: https://hexdocs.pm/elixir/Kernel.html#trunc/1
+
+## Instructions
+
+In this exercise you'll be writing code to help a freelancer communicate with a project manager by providing a few utilities to quickly calculate daily and
+monthly rates, optionally with a given discount.
+
+We first establish a few rules between the freelancer and the project manager:
+
+- The daily rate is 8 times the hourly rate.
+- A month has 22 billable days.
+
+Sometimes, the freelancer is offering to apply a discount on their daily rate (for example for their most loyal customers or for non-for-profit customers).
+
+Discounts are modeled as fractional numbers representing percentage, for example `25.0` (25%).
+
+## 1. Calculate the daily rate given an hourly rate
+
+Implement a function to calculate the daily rate given an hourly rate:
+
+```elixir
+FreelancerRates.daily_rate(60)
+# => 480.0
+```
+
+The returned daily rate should be a float.
+
+## 2. Calculate a discounted price
+
+Implement a function to calculate the price after a discount.
+
+```elixir
+FreelancerRates.apply_discount(150, 10)
+# => 135.0
+```
+
+The returned value should always be a float, not rounded in any way.
+
+## 3. Calculate the monthly rate, given an hourly rate and a discount
+
+Implement a function to calculate the monthly rate, and apply a discount:
+
+```elixir
+FreelancerRates.monthly_rate(77, 10.5)
+# => 12130
+```
+
+The returned monthly rate should be rounded up (take the ceiling) to the nearest integer.
+
+## 4. Calculate the number of workdays given a budget, hourly rate and discount
+
+Implement a function that takes a budget, an hourly rate, and a discount, and calculates how many days of work that covers.
+
+```elixir
+FreelancerRates.days_in_budget(20000, 80, 11.0)
+# => 35.1
+```
+
+The returned number of days should be rounded down (take the floor) to one decimal place.
+
+## Source
+
+### Created by
+
+- @angelikatyborska
+
+### Contributed to by
+
+- @neenjaw

elixir/freelancer-rates/lib/freelancer_rates.ex

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+defmodule FreelancerRates do
+  def daily_rate(hourly_rate) do
+    8.0 * hourly_rate
+  end
+
+  def monthly_rate(hourly_rate) do
+    22.0 * daily_rate(hourly_rate)
+  end
+
+  def monthly_rate(hourly_rate, discount) do
+    hourly_rate
+    |> monthly_rate()
+    |> apply_discount(discount)
+    |> ceil()
+  end
+
+  def apply_discount(before_discount, discount) do
+    before_discount - (before_discount * (discount / 100))
+  end
+
+  def days_in_budget(budget, hourly_rate, discount) do
+    hourly_rate
+    |> daily_rate()
+    |> apply_discount(discount)
+    |> then(fn rate -> budget / rate end)
+    |> Float.floor(1)
+  end
+end

elixir/freelancer-rates/mix.exs

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+defmodule FreelancerRates.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :freelancer_rates,
+      version: "0.1.0",
+      # elixir: "~> 1.10",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end

elixir/freelancer-rates/test/freelancer_rates_test.exs

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+defmodule FreelancerRatesTest do
+  use ExUnit.Case
+
+  describe "daily_rate/1" do
+    @tag task_id: 1
+    test "it's the hourly_rate times 8" do
+      assert FreelancerRates.daily_rate(50) == 400.0
+    end
+
+    @tag task_id: 1
+    test "it always returns a float" do
+      assert FreelancerRates.daily_rate(60) === 480.0
+    end
+
+    @tag task_id: 1
+    test "it does not round" do
+      assert FreelancerRates.daily_rate(55.1) == 440.8
+    end
+  end
+
+  describe "apply_discount/2" do
+    @tag task_id: 2
+    test "a discount of 10% leaves 90% of the original price" do
+      assert FreelancerRates.apply_discount(140.0, 10) == 126.0
+    end
+
+    @tag task_id: 2
+    test "it always returns a float" do
+      assert FreelancerRates.apply_discount(100, 10) == 90.0
+    end
+
+    @tag task_id: 2
+    test "it doesn't round" do
+      assert_in_delta FreelancerRates.apply_discount(111.11, 13.5), 96.11015, 0.000001
+    end
+  end
+
+  describe "monthly_rate/2" do
+    @tag task_id: 3
+    test "it's the daily_rate times 22" do
+      assert FreelancerRates.monthly_rate(62, 0.0) == 10_912
+    end
+
+    @tag task_id: 3
+    test "it always returns an integer" do
+      assert FreelancerRates.monthly_rate(70, 0.0) === 12_320
+    end
+
+    @tag task_id: 3
+    test "the result is rounded up" do
+      # 11_052.8
+      assert FreelancerRates.monthly_rate(62.8, 0.0) == 11_053
+      # 11_475.2
+      assert FreelancerRates.monthly_rate(65.2, 0.0) == 11_476
+    end
+
+    @tag task_id: 3
+    test "gives a discount" do
+      # 11_792 - 12% * 11_792 = 10_376.96
+      assert FreelancerRates.monthly_rate(67, 12.0) == 10_377
+    end
+  end
+
+  describe "days_in_budget/3" do
+    @tag task_id: 4
+    test "it's the budget divided by the daily rate" do
+      assert FreelancerRates.days_in_budget(1_600, 50, 0.0) == 4
+    end
+
+    @tag task_id: 4
+    test "it always returns a float" do
+      assert FreelancerRates.days_in_budget(520, 65, 0.0) === 1.0
+    end
+
+    @tag task_id: 4
+    test "it rounds down to one decimal place" do
+      # 10.02273
+      assert FreelancerRates.days_in_budget(4_410, 55, 0.0) == 10.0
+      # 10.18182
+      assert FreelancerRates.days_in_budget(4_480, 55, 0.0) == 10.1
+    end
+
+    @tag task_id: 4
+    test "it applies the discount" do
+      # 1.25
+      assert FreelancerRates.days_in_budget(480, 60, 20) == 1.2
+    end
+  end
+end

elixir/freelancer-rates/test/test_helper.exs

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+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true, seed: 0)