ShortMaps

⚠️ Important: short_maps has been retired from Hex. Read more about it in this blog post. The repository is also archived. If you have an issue with short_maps, please send me an email. ⚠️

Implementation of a ~m sigil for ES6-like maps in Elixir.

Rationale

ShortMaps is the result of a discussion in the Elixir mailing list. The topic of the discussion was the introduction of a syntax for maps similar to ES6 map syntax:

foo = 1
bar = 2

%{foo, bar} == %{foo: foo, bar: bar}
#=> true

The discussion on pros and cons went on for a while until @josevalim came up with a better solution (like he always does): using sigils.

foo = 1
bar = 2

~m(foo bar)a == %{foo: foo, bar: bar}
#=> true

Sigils allow to:

• be more explicit and declarative
• use both atom and string keys (using modifiers in the sigil)

This library is an attempt to implement this so that you can try it out.

Examples

Note that you always have to import ShortMaps for the sigil to work.

import ShortMaps

my_map = %{foo: 1, bar: 2, baz: 3}

~m(foo bar baz)a = my_map
foo #=> 1

import ShortMaps

name = "Meg"

# String keys by default (or with the 's' modifier)
~m(name) #=> %{"name" => "Meg"}
# Atom keys with the 'a' modifier
~m(name)a #=> %{name: "Meg"}

There is also support for pinning variables, if you want to do matching vs. their previous value:

iex(1)> import ShortMaps
nil
iex(2)> name = "Meg"
"Meg"
iex(3)> ~m(^name)a = %{name: "Meg"}
%{name: "Meg"}
iex(4)> ~m(^name)a = %{name: "Megan"}
** (MatchError) no match of right hand side value: %{name: "Megan"}

If you need to match on structs, the first word should be '%' followed by the name of the module:

iex(1)> import ShortMaps
nil
iex(2)> defmodule Foo do
...(2)>  defstruct bar: nil
...(2)>end
{:module, Foo,
 <<...>>,
 [bar: nil]}

iex(3)> ~m(%Foo bar)a = %Foo{bar: 5}
%Foo{bar: 5}
iex(4)> bar
5
iex(5)> ~m(%Foo ^bar)a = %Foo{bar: 12}
** (MatchError) no match of right hand side value: %Foo{bar: 12}

You can see more examples and read some docs in the docs for the sigil_m macro.

LICENSE

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org