New concept exercise city-office (docs and typespecs)

exercises/concept/city-office/.formatter.exs

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

exercises/concept/city-office/.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").
+match_binary-*.tar
+

exercises/concept/city-office/.meta/config.json

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+{
+  "blurb": "TODO",
+  "authors": [
+    {
+      "github_username": "angelikatyborska",
+      "exercism_username": "angelikatyborska"
+    }
+  ],
+  "contributors": [
+    {
+      "github_username": "neenjaw",
+      "exercism_username": "neenjaw"
+    }
+  ],
+  "files": {
+    "solution": [
+      "lib/form.ex"
+    ],
+    "test": [
+      "test/form_test.exs"
+    ],
+    "exemplar": [
+      ".meta/exemplar.ex"
+    ]
+  },
+  "language_versions": ">=1.10"
+}

exercises/concept/city-office/.meta/design.md

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+# Design
+
+## Learning objectives
+
+## Out of scope
+
+## Prerequisites
+
+## Concepts
+
+## Analyzer

exercises/concept/city-office/.meta/exemplar.ex

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+defmodule Form do
+  @moduledoc """
+  A collection of loosely related functions helpful for filling out various forms at the city office.
+  """
+
+  defmodule Address do
+    defstruct [:street, :postal_code, :city]
+
+    @type t() ::
+            %__MODULE__{
+              street: String.t(),
+              postal_code: String.t(),
+              city: String.t()
+            }
+  end
+
+  @doc """
+  Generates a string of a given length.
+
+  This string can be used to fill out a form field that is supposed to have no value.
+  Such fields cannot be left empty because a malicious third party could fill them out with false data.
+  """
+  @spec blanks(non_neg_integer()) :: String.t()
+  def blanks(n) do
+    String.duplicate("X", n)
+  end
+
+  @doc """
+  Splits the string into a list of uppercase letters.
+
+  This is needed for form fields that don't offer a single input for the whole string,
+  but instead require splitting the string into a predefined number of single-letter inputs.
+  """
+  @spec letters(String.t()) :: list(String.t())
+  def letters(word) do
+    word
+    |> String.upcase()
+    |> String.split("", trim: true)
+  end
+
+  @doc """
+  Checks if the value has no more than the maximum allowed number of letters.
+
+  This is needed for form fields that don't offer a single input for the whole string,
+  but instead require splitting the string into a predefined number of single-letter inputs.
+  """
+  @spec check_length(String.t(), non_neg_integer()) :: :ok | {:error, pos_integer()}
+  def check_length(word, length) do
+    diff = String.length(word) - length
+
+    if diff <= 0 do
+      :ok
+    else
+      {:error, diff}
+    end
+  end
+
+  @doc """
+  Formats the address as an uppercase multiline string.
+  """
+  @spec format_address(
+          Address.t()
+          | {street :: String.t(), postal_code :: String.t(), city :: String.t()}
+        ) :: String.t()
+  def format_address(%Address{} = address) do
+    format_address({address.street, address.postal_code, address.city})
+  end
+
+  def format_address({street, postal_code, city}) do
+    """
+    #{String.upcase(street)}
+    #{String.upcase(postal_code)} #{String.upcase(city)}
+    """
+  end
+end

exercises/concept/city-office/lib/form.ex

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+defmodule Form do
+  defmodule Address do
+    defstruct [:street, :postal_code, :city]
+  end
+
+  def blanks(n) do
+    String.duplicate("X", n)
+  end
+
+  def letters(word) do
+    word
+    |> String.upcase()
+    |> String.split("", trim: true)
+  end
+
+  def check_length(word, length) do
+    diff = String.length(word) - length
+
+    if diff <= 0 do
+      :ok
+    else
+      {:error, diff}
+    end
+  end
+
+  def format_address(%Address{} = address) do
+    format_address({address.street, address.postal_code, address.city})
+  end
+
+  def format_address({street, postal_code, city}) do
+    """
+    #{String.upcase(street)}
+    #{String.upcase(postal_code)} #{String.upcase(city)}
+    """
+  end
+end

exercises/concept/city-office/mix.exs

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+defmodule Form.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :city_office,
+      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