New subject: XRM 53: Add meta-if at Expression level.

12 Jun 2006

...
 >> "SIGOURE" == SIGOURE Benoit
&lt;sigoure.benoit(a)lrde.epita.fr&gt; writes: 

I don't think you need these two:

...
  +  EvalIf:
 +    |[ d ? e1 : e2 ]| -> |[ e1 ]|
 +    where <not(compare(real-eq))>(d, 0)
 +
 +  EvalIf:
 +    |[ d ? e1 : e2 ]| -> |[ e2 ]|
 +    where <compare(real-eq)>(d, 0)
 + 
Since

...
  +  LitToBool:
 +    |[ d ]| -> |[ false ]|
 +    where <compare(real-eq)>(d, 0)
 +
 +  LitToBool:
 +    |[ d ]| -> |[ true ]|
 +    where <not(compare(real-eq))>(d, 0) 
and

...
       ?MetaIf(condition, then-part, else-part)
      ///*DEBUG*/; say(!" @@@ eval-meta-if: starting:")
      ///*DEBUG*/; printf(|"     condition = ", condition)
 -    ; where(<prism-desugar> condition => condition-value)
 +    ; where(<prism-desugar> condition
 +           ; try(LitToBool) => condition-value)
      ///*DEBUG*/; printf(|"     condition-value = ", condition-value)
      ; if !condition-value => True() then
          <eval-meta-code> then-part 

Re: XRM 53: Add meta-if at Expression level.