Why can’t this be done with a sigil, which also has precedence for shorthands like this. Elixir even states that it is build to be extendable without the need for syntax changes. Personal I dislike prior art justifications for shorthands and syntax changes like this, as it can potentially block or limit syntax changes in the future for new data structures. I think we would all be better off with a sigil, that way we also don’t limit ourselves to atom keys.
On Sunday, December 21, 2025 at 5:07:33 PM UTC-5 [email protected] wrote: > 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. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/d/msgid/elixir-lang-core/995a7fec-5992-484a-88c2-5aae3844f60fn%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/elixir-lang-core/995a7fec-5992-484a-88c2-5aae3844f60fn%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/elixir-lang-core/7061e91f-b05c-40d3-8b46-5744e1a8f399n%40googlegroups.com.
