Luis Mario Monteiro Lopes - 2025-04-03

Hi,
I want to draw just the part of a line that satisfies a condition and when i use the implicit instruction the equation corresponding to the condition is also plot.
For instances, wanting to plot just the part of x^2+y^2-1=0 that satisfies x>y, i used

f(x,y):=if x>y then x^2+y^2-1 else -1$
draw2d(
    implicit(f(x,y),x,0,1,y,0,1)
    )$

and part of the x=y line is also plot :/
What am i doing wrong or how can i solve it?
Thanks