Plus and Minus operators

[Dan Wamba]

Hi,

I have some comments on eq...

I continue writing my large Lout document, which
includes a lot of maths also. I find Lout sometimes
wordy [which is necessary to keep it flexible] but
extremely useful :-)

Minor problem was: I was unhappy the eqf file defines
"+" and "-" as {bin plus} and {bin minus}, because
/silly example only/:

-C = 1 + 2 {first - is not binary}

is better than

 - C = 1 + 2 

But it was __easy__ to fix it

def "-"
left x
{
  @Case x
  {
    "" @Yield minus
    "(" @Yield {x minus}
    "[" @Yield {x minus}
    else @Yield {x bin minus}
  }
}


It works better than the default, I think.

I even wanted f(t+1) = f(t) - f(t-1) ...
/you think about it if you have a lot of such
equations/
And I have defined "-" in the way as follows therefore

def "-" 
left x 
right y 
{ 
        x @Case 
        { 
                "" @Yield {x minus y}
                ( @Yield {x minus y}
                [ @Yield {x minus y}
                t @Yield {x minus y}
                tau @Yield {x minus y} 
                else  @Yield
                {
                        y @Case
                        {
                                t @Yield {x minus y}
                                tau @Yield {x minus y}
                                else @Yield {x bin minus y}
                        } 
                }
        } 
}


That's not so nice :-(. I think it would
be better for "-" and "+" to obey the spaces around
them. I AM NOT ABLE TO PROGRAM THIS IN LOUT. Is it
possible or not? I was also surprised I have to write
f( t+1 ) to make "+" obvious that the left argument is
t and not f(t. Is that correct??? Where do objects
start? After a whitespace? 

I think it would be GREAT to introduce
1.  left word x
2.  left character x
3.  ???
...
Is that a good idea?

best regards
DANIEL

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