bindings & lazy-seq

[Carlos-K]

Hi,

Why when you create a lazy sequence, you need to do the bindings
inside the definition?, e.g.,

(lazy-seq
(binding [*in* in#]
<-- some code -->))

As opposed to make the bindings first and call the lazy-seq later,
e.g.,

(binding [*in* in#]
(lazy-seq
<-- some code -->))


Thanks

[Meikel Brandmeyer]

Hi,

This might help:
http://kotka.de/blog/2009/11/Taming_the_Bound_Seq.html

Sincerely
Meikel

[Mark Nutter]

I'll take a stab at this and then someone can tell me if I'm
understanding it myself.

> (lazy-seq
> (binding [*in* in#]
> <-- some code -->))

This is inside the definition, so it executes whenever you actually
USE the definition--i.e. it binds *in* to in# at the time the lazy seq
is used, which is probably what you want.

> (binding [*in* in#]
> (lazy-seq
> <-- some code -->))

This is outside the definition, so it executes and binds *in* to in#
at the time the lazy seq is defined. In other words, the binding ends
as soon as the lazy seq is defined, so when you go to actually use the
seq, the binding has ended, and *in* has its original value.

How'd I do?

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