undefined | Better HN

0 pointsbee_rider2y ago0 comments

I wonder why =+ is so obviously a mistake. It does look vaguely wrong for some reason, but I’m prejudiced by current languages.

0 comments

coldtea2y ago

>I wonder why =+ is so obviously a mistake

Consider

  x = -5

now how about:

  x =- 5

One makes x negative 5, the other subtracts 5 from it. And under this design of the operator the only difference is a space.

It's the same with +, just that we're not used to seeing unary plus in the wild.

thr0w__4w4y2y ago

>> x =- 5

I think you mean: x -= 5, which indeed is different.

coldtea2y ago

I'm showing how it would be under the original operator design which was reverted, which was "=-".

vgel2y ago

I think because it's ambiguous with unary plus (a = +b), since C isn't supposed to have significant whitespace in most circumstances.

tom_2y ago

You also run into problems with a=*p and a=-b, which are perhaps more likely.

zeusk2y ago

But they could've fixed that by going a=(*p) and a=(-b);

Kind of how we use (*p)->next instead of *p->next where p is node_t**

1 more reply

kazinator2y ago

But originally there wasn't a += or =+ lexical token! Those things were scanned as separate tokens, and could be written = +.

So that is problematic; If {a}{=}{-}{b} means a = a - b, then you have no way to write a = -b without parentheses like a = (-b).

j / k navigate · click thread line to collapse

0 comments

coldtea2y ago

>I wonder why =+ is so obviously a mistake

Consider

  x = -5

now how about:

  x =- 5

One makes x negative 5, the other subtracts 5 from it. And under this design of the operator the only difference is a space.

It's the same with +, just that we're not used to seeing unary plus in the wild.

thr0w__4w4y2y ago

>> x =- 5

I think you mean: x -= 5, which indeed is different.

coldtea2y ago

I'm showing how it would be under the original operator design which was reverted, which was "=-".

vgel2y ago

I think because it's ambiguous with unary plus (a = +b), since C isn't supposed to have significant whitespace in most circumstances.

tom_2y ago

You also run into problems with a=*p and a=-b, which are perhaps more likely.

zeusk2y ago

But they could've fixed that by going a=(*p) and a=(-b);

Kind of how we use (*p)->next instead of *p->next where p is node_t**

1 more reply

kazinator2y ago

But originally there wasn't a += or =+ lexical token! Those things were scanned as separate tokens, and could be written = +.

So that is problematic; If {a}{=}{-}{b} means a = a - b, then you have no way to write a = -b without parentheses like a = (-b).

j / k navigate · click thread line to collapse