Re: [Proposal] Overload | for booleans

["Soni L." <fakedme@...>]

On 29/07/15 01:11 PM, Sean Conner wrote:
> It was thus said that the Great Soni L. once stated:
> > On 29/07/15 11:18 AM, Dirk Laurie wrote:
> > > 2015-07-29 15:56 GMT+02:00 Soni L. <fakedme@gmail.com>:
> > >
> > > > Can we get true | false to be a thing?
> > > debug.setmetatable(true,{
> > >    __bor = function(x,y)
> > >      assert (type(x)=='boolean' and type(y)=='boolean')
> > >      return x or y
> > >    end;
> > >      __band = function(x,y)
> > >      assert (type(x)=='boolean' and type(y)=='boolean')
> > >      return x and y
> > >    end;
> > > })
> > >
> > > I like that! But why do you call it a proposal?
> > It would be non-short-circuiting and/or.
>    We already have those in the langauge, "and" and "or".  The operators "&",
> "|" and "~" work bitwise, not logic wise.  There's a reason why C has both
> "|" and "||" for "or".
>
>    -spc
"and" and "or" are the short-circuiting ones. they also do branching.

lua code
-----------------------
function t() print("true") return true end
function f() print("false") return false end

print(t() or f()) -- prints "true" and "true"

print(f() and t()) -- prints "false" and "false"

local left, right = t(), f() -- evaluate both sides, prints "true" and 
"false"
print(left or right) -- prints "true", after some branching

local left, right = f(), t() -- evaluate both sides, "false" and "true" now
print(left and right) -- prints "false", after some branching

C code
-------------------------
int t() {
  printf("true\n");
  return 1;
}
int f() {
  printf("false\n");
  return 0;
}
int main() {
  printf("%d", t() || f());
  printf("%d", f() && t());

  printf("%d", t() | f());
  printf("%d", f() & t());

  return 0;
}


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