Somewhere between a bug or feature:

[Mark Hardman]

(11-13-2014 10:43 PM)Han Wrote:  A few more trials leads me to think that perhaps you're onto something.

b:=x^2;
b+2*x|x=3; --> x^2+6
b|x=3; ---> 9

I can't explain this.

How is this?

b(x):=x^2
b(x)+2*x|x=3 --> 15