Guardsafe

Macros expanding into code that can be safely used in guard clauses.

Usage

Update your mix.exs file and run mix deps.get.

defp deps do
  [{:guardsafe, "~> 0.3.0"}]
end

Import all the macros...

defmodule MyModule do
  import Guardsafe

...or just the ones you need.

defmodule MyOtherModule do
  import Guardsafe, only: [divisible_by?: 2, integer?: 1]

Now go forth and make your guard clauses more readable!

def leap_year?(year) when not integer?(year), do: raise "That's not a proper year!"
def leap_year?(year) when divisible_by?(year, 400), do: true
def leap_year?(year) when divisible_by?(year, 100), do: false
def leap_year?(year), do: divisible_by?(year, 4)

Documentation for each macro is of course available in iex.

iex(1)> h Guardsafe.divisible_by?

                    defmacro divisible_by?(number, divisor)

Expands divisible_by?(number, divisor) into rem(number, divisor) == 0

Available macros

NB: If a macro is translated into a function residing in another module than Kernel you need to require it before use, e.g. require Integer.

Expressive calculations

• divisible_by?/2 - checks whether two integers are evenly divisible.

Macros for checking types

• atom?/1 - translates into Kernel.is_atom/1
• binary?/1 - translates into Kernel.is_binary/1
• bitstring?/1 - translates into Kernel.is_bitstring/1
• boolean?/1 - translates into Kernel.is_boolean/1
• float?/1 - translates into Kernel.is_float/1
• function?/1 - translates into Kernel.is_function/1
• function?/2 - translates into Kernel.is_function/2
• integer?/1 - translates into Kernel.is_integer/1
• list?/1 - translates into Kernel.is_list/1
• map?/1 - translates into Kernel.is_map/1
• nil?/1 - translates into Kernel.is_nil/1
• number?/1 - translates into Kernel.is_number/1
• pid?/1 - translates into Kernel.is_pid/1
• port?/1 - translates into Kernel.is_port/1
• reference?/1 - translates into Kernel.is_reference/1
• tuple?/1 - translates into Kernel.is_tuple/1

Macros for checking values

• even?/1 - translates into Integer.is_even/1
• odd?/1 - translates into Integer.is_odd/1

Why nil? and float? instead of is_nil and is_float

While the Elixir core team thinks that nil? compared to is_nil is an inconcistency, others, especially Rubyists, are more comfortable with the nil? notation.

Online documentation

For more information, see the full documentation.