import graph;
size(7.5cm,0);

real[] x={ -3 , -2   , 0 , 1 , 2 },
       y={ -2 , -1.5 , 3 , 4 , 4 };
                              
// Deux abréviations utiles : Spline et Straight (par défaut)
guide courbe1=graph(x,y,Straight), // join=operator --
      courbe2=graph(x,y,Spline);   // join=operator ..

dot(courbe1,3bp+blue);
draw(courbe1,red);
draw(courbe2,.5green+linetype("4 4"));

xaxis("$x$",Ticks("%",end=false),Arrow());
yaxis("$y$",Ticks("%",end=false),Arrow());