Re: [RFC]Discuss] Syntax for Arrow Functions

On Tuesday, May 30, 2017 at 12:58 PM, Levi Morrison wrote: > Based on the discussion there are a few different syntax choices > people liked. Overall it's a feature that people seem to want but > everyone seems to prefer a different syntax choice. > > 1. fn(params) => expr > 2. function(params) => expr > 3. (params) ==> expr > 4. (params) => expr > 5. > [](params) => expr // binds no values > [=](params) => expr // binds by value > [&](params) => expr // binds by reference As a userland developer, I've been waiting/hoping for short arrow functions for a long time! Option 3 seems like the most obvious choice, since that's the same syntax Hack uses. Would it be very difficult to implement the parser changes necessary for this syntax? Or is there some other downside to a more powerful grammar/parser (e.g. worse performance)? If option 3 isn't viable, my next preference would be option 1. Presumably the drawback of a new symbol is that it might break existing code using fn as the name of a class or function. However, using a new symbol would arguably enable more readable code than the other options. Option 2 is not only lengthy, but it also could be confusing since it reuses the function symbol for something that isn't a normal function. Option 5 seems overly complex and hard to read. Whether option 1, 2, or 3 is used, to me it seems that capturing by reference would be the most useful and intuitive behavior. It's intuitive since implicit capture makes it feel like all the captured variables are in the same scope.