Feature #16898: Modify the syntax of -> lambda expressions in ruby3

• Status: Open
• Assignee: -
• Target version: -

[jackmaple (maple jack)]

Hello ruby team.
Can we modify the syntax of lambda expressions in ruby3?
The current definition of lambda expression was added in ruby1.9, but this syntax looks too tedious.

lambda {|x| x + 1}   #This looks elegant.
#but...In lambda expression body, when there is only one line of statement
-> x {x + 1}    #Can the braces be removed?
-> x do x + 1 end  #As above, can the do ... end block be removed?

So are we going to abandon some historical issues? To modify -> lambda syntax?
It looks like this:

x -> x + 1
(x,y) -> x + y
x -> y -> x + y
x -> {
   x + 1
   x + 2
}

I think do..end or braces are only needed when there are multiple lines of code,lambda expression if there is only one statement should not need parentheses or do ... end block.
Thanks.

[jackmaple (maple jack)]

• Description updated (diff)

[jackmaple (maple jack)]

• Description updated (diff)

[matz (Yukihiro Matsumoto)]

"Ugliness is in the eye of the beholder". Could you explain why the current syntax is ugly?

In any case, if we change the syntax, all Ruby programs that use the current ugly lambda syntax no longer work. How do you think? Is it worth the pain of the whole Ruby community?

Matz.

[shan (Shannon Skipper)]

To me, this

-> lightness { lightness }

Is prettier than

lambda { |lightness| lightness  }

¯\(ツ)/¯

I like stabby lambdas, but it doesn't seem worth the pain of the massive code breakage even if we all agreed they're ugly.

matz (Yukihiro Matsumoto) wrote in #note-3:

"Ugliness is in the eye of the beholder".

-> (;x) { x = 1 } # correct
->  ;x  { x = 1 } # syntax error

Is the second uglier?

[jackmaple (maple jack)]

matz (Yukihiro Matsumoto) wrote in #note-3:

"Ugliness is in the eye of the beholder". Could you explain why the current syntax is ugly?

In any case, if we change the syntax, all Ruby programs that use the current ugly lambda syntax no longer work. How do you think? Is it worth the pain of the whole Ruby community?

Matz.

Hello, we currently have lambda syntax, but at present-> seems to be just a simplified alternative,-> The braces behind cannot be omitted when there is only one line of statement, maybe we can add a new lambda syntax, thank you

#1 -> x {x}
#2 x -> x

I think the second way of writing can omit curly braces in only one expression.Of course this is just my suggestion,I respect your decision.thank you very much.

[shyouhei (Shyouhei Urabe)]

Not going to join the ugliness debate but I doubt if the proposed new syntax technically possible. It would be much convincing if you provide a working pull request.

[jackmaple (maple jack)]

• Description updated (diff)

[jackmaple (maple jack)]

• Description updated (diff)

[jackmaple (maple jack)]

Maybe my expression has some problems, sorry, it has been modified, in fact, what I want to say is that the existing lambda expression looks like the arrow symbol is not very intuitive.
If we can simplify the grammar, in some cases it would be better to remove the braces?

-> x x   # error
-> x {x} # correct

So it would be better if we could provide a grammar with braces removed?In order to maintain compatibility, it is not necessary to modify the existing grammar.
For example, add a new lambda operator "==>"?

-> x {x}
lambda {|x| x}
x ==> x     # suppose

What do you think?
thanks.

[matz (Yukihiro Matsumoto)]

I get your point. But to my eyes, ==> is even uglier. It's easily confused with other operators which do not correspond with lambdas but association operators (hash rockets) or comparison operators.
I am not yet convinced having a new lambda operator without braces around the body is that important, despite the possibility of the above confusion.

Matz.