happy with

Author: vic

.gitignore

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+/_build
+/cover
+/deps
+erl_crash.dump
+*.ez

README.md

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+# HappyWith
+
+Tiny syntax sugar around Elixir's `with` special form.
+
+#### Why ?
+
+Because I'm happy on how Elixir's `with` special form works, 
+and can get used to the `<-` arrow but I still dont like to
+place commas between all the with expressions. 
+
+Back then before elixir 1.2 release, I implemented [happy](http://github.com/vic/happy) using case
+expressions, it leaked variables as normal case expressions would do, and _overriding_ the standard
+`=` operator turned out to have some unexpected cases. Also, after using standard `with` a bit, I
+really got to like it, except for the fact of having to place commas after expressions, so I wrote
+`happy_with` which is a *very* tiny macro that just rewrites to Elixir's standard `with` special form.
+
+## Installation
+
+[Available in Hex](https://hex.pm/packages/happy_with), the package can be installed as:
+
+  1. Add happy_with to your list of dependencies in `mix.exs`:
+
+```elixir
+def deps do
+  [{:happy_with, "~> 0.0.1"}]
+end
+```
+        
+## Usage
+
+```elixir
+import HappyWith
+```
+
+#### `happy_with` macro
+
+```
+happy_with do
+  {:ok, friend} <- retrieve_friend
+  name = String.downcase(friend)
+  name
+else
+  _ -> "nobody"
+end
+```
+
+rewrites into standard `with` form.
+Only the last expression in the happy_with block is given to with's do.
+
+```elixir
+with({:ok, friend} <- retrieve_friend,
+     name = String.downcase(friend))
+do
+  name
+else
+  _ -> "nobody"
+end
+```
+
+IMHO the first one reads better.

config/config.exs

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+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+use Mix.Config
+
+# This configuration is loaded before any dependency and is restricted
+# to this project. If another project depends on this project, this
+# file won't be loaded nor affect the parent project. For this reason,
+# if you want to provide default values for your application for
+# 3rd-party users, it should be done in your "mix.exs" file.
+
+# You can configure for your application as:
+#
+#     config :happy_with, key: :value
+#
+# And access this configuration in your application as:
+#
+#     Application.get_env(:happy_with, :key)
+#
+# Or configure a 3rd-party app:
+#
+#     config :logger, level: :info
+#
+
+# It is also possible to import configuration files, relative to this
+# directory. For example, you can emulate configuration per environment
+# by uncommenting the line below and defining dev.exs, test.exs and such.
+# Configuration from the imported file will override the ones defined
+# here (which is why it is important to import them last).
+#
+#     import_config "#{Mix.env}.exs"

lib/happy_with.ex

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+defmodule HappyWith do
+
+  @doc ~S"""
+  Rewrites the given block and else clauses into Elixir's standard `with` form.
+
+    iex> import HappyWith
+    iex> happy_with do
+    ...>   {:ok, name} <- {:ok, "joSE"}
+    ...>   lower = String.downcase(name)
+    ...>   lower
+    ...> end
+    "jose"
+
+
+  You can also provide else clauses to the `with` form.
+
+
+    iex> import HappyWith
+    iex> happy_with do
+    ...>   {:ok, name} <- {:error, :nobody}
+    ...>   _never_reached = String.downcase(name)
+    ...> else
+    ...>   {:error, _} -> "luis"
+    ...> end
+    "luis"
+
+
+  """
+  defmacro happy_with([do: {:__block__, _, body}, else: elses]), do: rewrite(body, elses)
+  defmacro happy_with([do: {:__block__, _, body}]), do: rewrite(body, nil)
+
+  defp rewrite(body, elses) when length(body) > 1 do
+    exprs = Enum.slice(body, 0..-2)
+    do_last = [do: Enum.at(body, -1)]
+    else_clauses = elses && [else: elses] || []
+    {:with, [], exprs ++ [do_last ++ else_clauses]}
+  end
+
+  defp rewrite(body, _elses), do: body
+
+end

mix.exs

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+defmodule HappyWith.Mixfile do
+  use Mix.Project
+
+  def project do
+    [app: :happy_with,
+     version: "0.0.1",
+     elixir: "~> 1.2",
+     description: description,
+     package: package,
+     build_embedded: Mix.env == :prod,
+     start_permanent: Mix.env == :prod,
+     deps: deps]
+  end
+
+  def package do
+    [files: ~w(lib mix.exs README* LICENSE),
+     maintainers: ["Victor Hugo Borja <[email protected]>"],
+     licenses: ["Apache 2.0"],
+     links: %{
+       "GitHub" => "https://github.com/vic/happy_with"
+     }]
+  end
+
+  def description do
+    """
+    Tiny syntax sugar around Elixir's `with` special form.
+
+    Dont use commas around with expressions.
+    """
+  end
+
+  # Configuration for the OTP application
+  #
+  # Type "mix help compile.app" for more information
+  def application do
+    [applications: [:logger]]
+  end
+
+  # Dependencies can be Hex packages:
+  #
+  #   {:mydep, "~> 0.3.0"}
+  #
+  # Or git/path repositories:
+  #
+  #   {:mydep, git: "https://github.com/elixir-lang/mydep.git", tag: "0.1.0"}
+  #
+  # Type "mix help deps" for more examples and options
+  defp deps do
+    []
+  end
+end

test/happy_with_test.exs

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+defmodule HappyWithTest do
+  use ExUnit.Case
+
+  doctest HappyWith
+end

test/test_helper.exs

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+ExUnit.start()