You need to quote the entire vector `avec`, because otherwise the function
you want to bind to `foo` will be evaluated before being evaluated by the
`let` special operator, which expects only standard readable object
literals to be embedded.
Try changing:
(def avec
['p true
'foo (fn
Hi Adrian,
with your suggestion it certainly works also with avec'
however, I still don't see why the original code from Burt works with avec
and does not work with avec'
cheers,
Gianluca
On Thursday, January 14, 2016 at 5:06:02 PM UTC+1, adrian...@mail.yu.edu
wrote:
>
> You need to quote
Hi,
I got an exception using eval and I do not understand why!
Can anybody explain what happens?
Here is a small piece of code showing the problem:
(defn eval-phi [avec phi]
(eval `(let ~avec ~phi)))
; The idea of eval-phi is the evaluation of
; arbitrary lists where the symbols are
;
Hi Burt,
I have done some investigation, further reducing your issue to the
following:
(def g (make-adder 2))
(eval `(let [~'f ~g] (~'f 5)))
; --> error IllegalArgumentException No matching ctor found for class
user$make_adder$fn__7609 etc.
(defn h [x] (+ x 2))
(eval `(let [~'f ~h] (~'f 5)))
Hi Adrian, Gianluca,
I understand that quoting the entire binding vector avec solves my
problem.
@Adrian Thanks for the hint.
But nethertheless, it's a riddle for me why there's a difference between my
original approaches.
cheers,
Burt
--
You received this message because you are
small update: I found that the problem happens because make-adder returns a
closure; with a simple function it works:
(defn make-2-adder [] (fn [x] (+ 2 x)))
(def g2 (make-2-adder))
(eval `(let [~'f ~g2] (~'f 5)))
; --> 7
On Thursday, January 14, 2016 at 12:52:47 PM UTC+1, gianluca torta
