Ruby Forum Ruby-core > Re: lambda, ->, haskell, and so on

> Is it too late for Ruby 1.9 to support lambdas that look like
> 
>    \ p1, p1 -> { block }

Not being a Haskell user, I have to ask: did you mean to write a block 
with
two parameters, like this?

    \ p1, p2 -> { block }

If not, it's a violation of DRY :-)

To me, backslash looks like an escaping operator (in strings and 
regexps, or
avoiding newline splits). So personally I find it ugly and unnatural.

As an example, presumably we talking about writing

    doit(\ p1, p2 -> { p1 + p2 }, \ msg -> { puts msg })

instead of

    doit(lambda { |p1, p2| p1 + p2 }, lambda { |msg| puts msg })

?

I generally use proc{...} anyway, even if it does have slightly 
different
semantics.

You could always take a leaf out of Paul Graham's book:
http://www.paulgraham.com/arcll1.html

"in Arc, lambda is called fn. This idea appalled me at first, but it 
seemed
like fn would be shorter and at least as expressive. What if I was just 
used
to lambda? So, with a queasy sense of duty, I decided to try it. And 
after a
few days I actually liked fn better. Now it seems clear to me that 
lambda is
an onion: Alonzo Church himself wouldn't have used it if he had to write 
out
the word lambda each time."

But at the end of the day, I'd vote for removing alternative syntaxes
altogether. It becomes harder to sell Ruby if there are too many 
equivalent
but different idioms to learn.

That's unless it's part of a grand unification plan (e.g. block 
parameters
gain optional/default arguments, and def methods become blocks). But I 
don't
think that's the case here.

Regards,

Brian.

On Thu, May 1, 2008 at 9:50 AM, Brian Candler <B.Candler@pobox.com> 
wrote:

> But at the end of the day, I'd vote for removing alternative syntaxes
> altogether. It becomes harder to sell Ruby if there are too many
> equivalent
> but different idioms to learn.
>

yeah. I'd vote for removing the "do end" syntax for blocks too ;). I 
always
found it hard to visually distinguish blocks from other constructs like 
if
and for when they are written as "do .... end" as compared to { ... }. 
So I
became a do-end hater. But as I know there are a lot of people who love
do-end there is probably no way to remove them from the language.

-- henon

Hi --

On Thu, 1 May 2008, Meinrad Recheis wrote:

> and for when they are written as "do .... end" as compared to { ... }. So I
> became a do-end hater. But as I know there are a lot of people who love
> do-end there is probably no way to remove them from the language.

They're also not identical to {}:

irb(main):001:0> puts [1,2,3].map do |x| x * 10 end
1
2
3

irb(main):002:0> puts [1,2,3].map {|x| x * 10 }
10
20
30


David