LISP to Ruby translation

ruby-talk
1

Jut a quick one, how do you translate this:

((if (zero? 0) + -) 3 4)
=> 7

to Ruby?

Cheers,
Douglas

2

Douglas Livingstone wrote:

Jut a quick one, how do you translate this:

((if (zero? 0) + -) 3 4)
=> 7

to Ruby?

Cheers,
Douglas

3.send(x.zero? ? :+ : :-, 4)

It's a little hard to read with all those colons. Maybe this is better:

3.send(if x.zero? then :+ else :- end, 4)

Or you could replace symbols with strings for readability, at a cost to speed:

p 3.send(x.zero? ? "+" : "-", 4)

···

--
        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

3

Douglas Livingstone wrote:

Jut a quick one, how do you translate this:

((if (zero? 0) + -) 3 4)
=> 7

to Ruby?

Well, these kind of questions are rarely helpful; translating an
idiomatic expression out of context from one language is often useless,
because in a greater context the ruby code might be doing something
completely different to begin with.

But, if you want a one-liner...

3.method(0.zero? ? :+ : :-).call(4)

···

--
Neil Stevens - neil@hakubi.us

'A republic, if you can keep it.' -- Benjamin Franklin

4

7 if true

--Steve

···

On Dec 14, 2005, at 6:36 PM, Douglas Livingstone wrote:

((if (zero? 0) + -) 3 4)
=> 7

to Ruby?

5

Douglas Livingstone wrote:

Just a quick one, how do you translate this:

((if (zero? 0) + -) 3 4)

What dialect of LISP is that? Not Common... CL has no "zero?"
(it's "zerop"), and + and - refer to input history rather than the functions
associated with the operators. To do something like that in CL I think
you have to use the characters '+ and '- and an (eval)...

6

Stephen Waits wrote:

((if (zero? 0) + -) 3 4)
=> 7

to Ruby?

7 if true

--Steve

7

···

On Dec 14, 2005, at 6:36 PM, Douglas Livingstone wrote:

--
      vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407

7

It's Scheme. A much nicer dialect than CL, IMHO. :wink:

I think in CL the equivalent would be:

((if (zerop 0) #'+ #'-) 3 4)

Note the ugly sharp-quotes, due to the fact that CL has separate
namespaces for values and functions.

regards,
Ed

···

On Fri, Dec 16, 2005 at 07:22:39AM +0900, Mark J.Reed wrote:

Douglas Livingstone wrote:
> Just a quick one, how do you translate this:
>
> ((if (zero? 0) + -) 3 4)

What dialect of LISP is that? Not Common... CL has no "zero?"

8

There - who says ruby isn't concise!

martin

···

Joel VanderWerf <vjoel@path.berkeley.edu> wrote:

Stephen Waits wrote:
>
> On Dec 14, 2005, at 6:36 PM, Douglas Livingstone wrote:
>
>> ((if (zero? 0) + -) 3 4)
>> => 7
>>
>> to Ruby?
>
>
> 7 if true
>
> --Steve

7

9

Edward Faulkner <ef@alum.mit.edu> writes:

Douglas Livingstone wrote:
> Just a quick one, how do you translate this:
>
> ((if (zero? 0) + -) 3 4)

What dialect of LISP is that? Not Common... CL has no "zero?"

It's Scheme. A much nicer dialect than CL, IMHO. :wink:

I think in CL the equivalent would be:

((if (zerop 0) #'+ #'-) 3 4)

No, you need:

  (apply (if (zerop 0) #'+ #'-) '(3 4))

Note the ugly sharp-quotes, due to the fact that CL has separate
namespaces for values and functions.

And that is why. :slight_smile:

···

On Fri, Dec 16, 2005 at 07:22:39AM +0900, Mark J.Reed wrote:

regards,
Ed

--
Christian Neukirchen <chneukirchen@gmail.com> http://chneukirchen.org