On Jan 15, 2010, at 4:01 AM, Stephen C. Gilardi wrote:
> On Jan 15, 2010, at 3:26 AM, Sean Devlin wrote:
>
>> user=> (seq [])
>> nil
>>
>> Why is nil returned, instead of an empty sequence?
>
> There is no such thing as an empty seq.
This was true at one time, but isn't true after the changes
Hi Sean,
The background to this lies in the implementation of lazy sequences -
seq returns an implementation of ISeq for the data structure in
question - nil when there are no elements in the structure. Have a
look at http://clojure.org/sequences and also http://clojure.org/lazy
which gives the fu
On Jan 15, 2010, at 3:26 AM, Sean Devlin wrote:
> user=> (seq [])
> nil
>
> Why is nil returned, instead of an empty sequence?
It's fundamental to Clojure's seq abstraction that every seq has a first. There
is no such thing as an empty seq. If you call the seq function on an empty
collection,
Hey,
I guess because a sequence is not a datastructure.
If there is nothing to iterate over via 'first or 'next, then it's nil.
And an "empty sequence" is precisely that: nil.
In my point of view, a sequence is more like a "functional iterator":
calling first on it will always return the same va
Hey everyone,
I was working with seq today, and I was wondering why I got a certain
result.
user=> (seq [])
nil
Why is nil returned, instead of an empty sequence?
Sean
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