Gentlemen---
Thanks for fixing my newbish error and showing me a better way to
do it!
Nick.
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> Unless you want the default value for a non initialized boolean value to be
> true ...
>
> (let [x (or false true)] => whooops
>
In defense: ad hoc solutions don't need 100% coverage,
mea culpa: I shouldn't have switched to it in discussing the macro.
mea maxima culpa: I hesitated mentioning
On Mon, Jul 27, 2009 at 8:33 PM, nchubrich wrote:
> Anyway I'd appreciate any critiques of the implementation; whether
> it's a useful thing or not; if there are more idiomatic ways of doing
> the same thing; and, if yes-no to the aforetwo, where's the best place
> to add this functionality?
W
Hi,
as David has said, your macro works only for literal
values, which doesn't make much sense.. I would
implement i-let as follows:
(defmacro let-default
[bindings & body]
`(let ~(vec (mapcat (fn [[sym value default]]
`(value# ~value
~sym
2009/7/28 David Miller
>
> (let [ x (or nil 4)
>y (or 2 6)
>z (or nil 10)]
> (+ x y z))
>
> => 16
>
> This use of 'or' is fairly idiomatic, and not just in Lispish. Less
> typing than 'if'. And you can use it or not, unlike i-let, which
> forces you to put in a default for all
(let [ x (or nil 4)
y (or 2 6)
z (or nil 10)]
(+ x y z))
=> 16
This use of 'or' is fairly idiomatic, and not just in Lispish. Less
typing than 'if'. And you can use it or not, unlike i-let, which
forces you to put in a default for all bindings.
Regarding the implementation of
I've been learning Clojure. I just wrote a macro to be used like so:
(i-let [x nil 4
y 2 6
z nil 10]
(+ x y z))
=> 16
I.E. if the first value in the triple is nil, bind it to the second
value in the triple. This is useful when you want to let something
that might be nil and
