Feature request: Ruby lambdas

[firedev]

Hi,

Not sure if it goes to SplitJoin or Switch or both. Maybe first transformation can be done in Switch and the second one in SplitJoin.

It would be great if I could get rid of the old Ruby lambda syntax lambda { |x| } and convert:

lambda { |x| whatever(x) }

↓

->(x) { whatever(x) }

This is one-way transformation. But the next one should be reversible:

->(x) { whatever(x) }

↕

lambda do |x|
  whatever(x)
end

Please let me know what you think as this might be hard to make.

[AndrewRadev]

I've just pushed an implementation of switching between the one-line lambda { |x| } syntax and ->(x) { }. I think this actually solves your problems, since you should be able to split the lambda into a do-end lambda by using splitjoin's standard block-syntax-split. The same thing goes for splitting ->(x) { } into a do-end form, if you feel like it.

Could you play around with this and let me know if it does the trick for you?

[AndrewRadev]

So, just to be clear of the process I'm thinking of:

# Start with:
lambda { |x| whatever(x) }
# After switch:
->(x) { whatever(x) }

# Now, let's go the other way

# First, switch
lambda { |x| whatever(x) }
# Then, split from splitjoin:
lambda do |x|
  whatever(x)
end

# And we can go back to the -> syntax with:

# join:
lambda { |x| whatever(x) }
# switch:
->(x) { whatever(x) }

[firedev]

Sorry I am offline right now. Maybe I messed it up myself. I need to check if it's correct. I think multiline lambda in ruby is written using curly braces only.

[firedev]

Doesn't work if it's spelled without space, which I find quite often in old code:

lambda{ ... }

[AndrewRadev]

It seems like the issue with the space is fixed now, I'm sorry it took so long to respond. I'm guessing I fixed it a while ago, but who knows.

[AndrewRadev]

I think I managed to implement this, and the lambda space issue seems to have been fixed, so I guess I'll go ahead and close this.