I wish for this often.
I would happily settle for this just to have it, although I don’t like the
syntax and also prefer the %{a, b} syntax like other languages (JS/TS,
Rust, ...)
On Sunday, December 21, 2025 at 2:12:13 AM UTC-4 [email protected]
wrote:
> I'm in support of this 👌
>
> It's a reasonable trade off from other concerns and as someone who works
> with people moving from other languages to Elixir often, they are
> *constantly* looking for this syntax. Given that this exact syntax is used
> in other languages also adds some regularity to it, despite my personal
> preference for js style %{a, b}. The "accidentally being a tuple" issue
> with that syntax goes away for 99% of cases conveniently with the type
> system FWIW :)
>
>
> On Sun, Dec 21, 2025 at 10:58 AM, Danila Poyarkov <[email protected]>
> wrote:
>
>> Hi everyone,
>>
>> José Valim suggested I move the discussion here from my PR:
>> https://github.com/elixir-lang/elixir/pull/15023
>>
>> I've implemented shorthand syntax for atom-keyed maps and keywords:
>>
>> ```elixir
>> %{user:, conn:} # => %{user: user, conn: conn}
>> [foo:, bar:] # => [foo: foo, bar: bar]
>> f(name:, age:) # => f(name: name, age: age)
>> %{map | a:, b:} # => %{map | a: a, b: b}
>> ```
>>
>> I know this topic has been discussed many times before:
>>
>> - Proposal: Short Hand Property Names (2017):
>> https://groups.google.com/g/elixir-lang-core/c/XxnrGgZsyVc
>> - Consider supporting a map shorthand syntax (2018):
>> https://groups.google.com/g/elixir-lang-core/c/NoUo2gqQR3I
>> - ES6-ish property value shorthands for maps? (2016):
>> https://elixirforum.com/t/es6-ish-property-value-shorthands-for-maps/1524
>> - Has Map shorthand syntax caused you any problems? (2018):
>> https://elixirforum.com/t/has-map-shorthand-syntax-in-other-languages-caused-you-any-problems/15403
>>
>> Most of these discussed the ES6-style `%{a, b}` syntax, which José made
>> clear had "zero chance" of being accepted — mainly because `%{a, b}` vs
>> `{a, b}` differs by one character, making maps and tuples too easy to
>> confuse.
>>
>> The colon-based syntax `%{a:, b:}` is different. The `:` that signals
>> "this is a key-value pair" stays there. There's no visual confusion with
>> tuples because `{a:, b:}` is not valid Elixir syntax anyway.
>>
>> José mentioned in the PR that he actually prefers this approach over bare
>> variables, but it was "deemed not acceptable by most people" in a previous
>> discussion. I'd like to understand what the objections were.
>>
>> Reading through the old threads, I found these concerns:
>>
>> - "Removing explicitness for the sake of brevity doesn't appeal to me."
>> (Chris Keathley)
>> - "Shorthand syntax makes that coupling even less obvious" — if you
>> change a key, you need to find all functions that relied on that variable
>> name. (Chris Keathley)
>> - "This will just add complexity to the language to save a few keystrokes
>> for advanced users." (Matt Widmann)
>>
>> These discussions happened in 2016-2018. Since then, Ruby 3.1 shipped
>> this exact syntax in December 2021 — almost 4 years ago. The syntax is
>> `{x:, y:}` for hashes and `foo(x:, y:)` for keyword arguments, exactly what
>> I'm proposing for Elixir.
>>
>> The Ruby reception was mixed at first — Bozhidar Batsov (RuboCop
>> maintainer) was critical (
>> https://batsov.com/articles/2022/01/20/bad-ruby-hash-value-omission/)
>> but still allowed it in RuboCop defaults. Four years later, the syntax is
>> widely used.
>>
>> The same pattern (sometimes called "field punning") also exists in Rust
>> and OCaml.
>>
>> `%{user: user, conn: conn}` is already common in Elixir — this just
>> removes the repetition. The colon stays visible, so it's not as "magic" as
>> the bare variable approach. And Ruby has been using it for 4 years now
>> without issues.
>>
>> The implementation is ready and all tests pass. I'm curious whether
>> opinions have changed since 2018.
>>
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>>
>
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