\usepackage {pstcol}
\begin{pspicture}(0,0)(3,2)\showgrid
  \psdots[linecolor=blue,dotstyle=triangle,
          dotscale=2](0,0.5)(1,2)(2.8,1.5)
  \pscurve[linecolor=cyan,showpoints=true]
          {->}%
          (0,1.2)(1.3,1.8)(3,0.4)(0.5,0.2)
\end{pspicture}