21 Jun
2006
21 Jun
'06
10:23 a.m.
On 2006-06-19, Akim Demaille <akim(a)lrde.epita.fr> wrote:
Because it's different here. All the evaluation stuff is in prism-desugar,
but here I don't want to prism-desugar everything. That's why the traversal
made by eval-meta-code does that `lazy' evaluation of logical operators `by
hands' (in fact it does rely on prism-desugar).
I'm not sure whether I've been clear :s
--
SIGOURE Benoit aka Tsuna
_____
/EPITA\ Promo 2008.CSI Rock & tRoll
>>
"SIGOURE" == SIGOURE Benoit <sigoure.benoit(a)lrde.epita.fr> writes:
https://svn.lrde.epita.fr/svn/xrm/trunk
Index: ChangeLog
from SIGOURE Benoit <sigoure.benoit(a)lrde.epita.fr>
Add lazy and/or evaluation at the meta-level.
One can now rely on laziness of logical operators to prevent what
could be an error at the meta-level, eg: x > 0 & s[x-1]=0
Brilliant, thanks!
eval-meta-code =
eval-meta-if
+ <+ lazy-eval-and
+ <+ lazy-eval-or
<+ unroll-meta-for
<+ unroll-meta-forin
<+ (expand-pformulas; eval-meta-code) // try again on expansed code.
@@ -72,6 +81,26 @@
end
end
+ lazy-eval-and =
+ ?|[ e1 & e2 ]|
+ ; <prism-desugar> e1
+ ; try(LitToBool) => e1'
+ ; if !e1' => False() then
+ !False()
+ else
+ fail
+ end
+
+ lazy-eval-or =
+ ?|[ e1 | e2 ]|
+ ; <prism-desugar> e1
+ ; try(LitToBool) => e1'
+ ; if !e1' => True() then
+ !True()
+ else
+ fail
+ end
I'm surprised not to see some code removed: I believe you are already
handling things such as "true & e" elsewhere.