* how far does eval go when module gets compiled?
@ 2016-01-12 4:52 Matt Wette
2016-01-12 7:56 ` Taylan Ulrich Bayırlı/Kammer
0 siblings, 1 reply; 3+ messages in thread
From: Matt Wette @ 2016-01-12 4:52 UTC (permalink / raw)
To: guile-user
When a module is compiled to generate a .go file is it possible to know (predict) what will be evaluated?
For example
(define-module (foo) #:export (bar))
(define bar (+ 3 4))
Is the “+” executed at compile time or at load time?
Matt
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: how far does eval go when module gets compiled?
2016-01-12 4:52 how far does eval go when module gets compiled? Matt Wette
@ 2016-01-12 7:56 ` Taylan Ulrich Bayırlı/Kammer
2016-01-12 19:52 ` Ludovic Courtès
0 siblings, 1 reply; 3+ messages in thread
From: Taylan Ulrich Bayırlı/Kammer @ 2016-01-12 7:56 UTC (permalink / raw)
To: Matt Wette; +Cc: guile-user
Matt Wette <matthew.wette@verizon.net> writes:
> When a module is compiled to generate a .go file is it possible to know (predict) what will be evaluated?
>
> For example
>
> (define-module (foo) #:export (bar))
>
> (define bar (+ 3 4))
>
> Is the “+” executed at compile time or at load time?
Nothing is really evaluated during compilation. (Not counting
optimization like partial evaluation.)
The "top-level" of a module is evaluated once when the module is loaded
into the run-time, whether it's in source form or a compiled .go.
So the "(+ 3 4)" in your example is (theoretically) evaluated when some
piece of code containing e.g. (use-modules (foo)) is executed, and the
module was not already loaded into the running Guile process. (Although
due to optimization, that "(+ 3 4)" will probably be turned into 7 at
compile-time.)
Note that there is a macro called 'eval-when' which can let you
explicitly evaluate expressions at compile-time.
And of course, all macro procedures get evaluated at compile-time to
transform the compiled code as desired.
Hope that helps,
Taylan
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: how far does eval go when module gets compiled?
2016-01-12 7:56 ` Taylan Ulrich Bayırlı/Kammer
@ 2016-01-12 19:52 ` Ludovic Courtès
0 siblings, 0 replies; 3+ messages in thread
From: Ludovic Courtès @ 2016-01-12 19:52 UTC (permalink / raw)
To: guile-user
taylanbayirli@gmail.com (Taylan Ulrich "Bayırlı/Kammer") skribis:
> So the "(+ 3 4)" in your example is (theoretically) evaluated when some
> piece of code containing e.g. (use-modules (foo)) is executed, and the
> module was not already loaded into the running Guile process. (Although
> due to optimization, that "(+ 3 4)" will probably be turned into 7 at
> compile-time.)
Right:
--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> ,optimize (lambda (x) (+ 3 4))
$2 = (lambda (x) 7)
--8<---------------cut here---------------end--------------->8---
Ludo'.
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