$\forall$${\it ds}$:$x$:Id fp$\rightarrow$ Type, ${\it da}$:$k$:Knd fp$\rightarrow$ Type, $x$:ecl(${\it ds}$;${\it da}$).
\\[0ex]($\uparrow$eclcatch?($x$)) $\Rightarrow$ (eclcatch{-}l($x$) $\in$ ($\mathbb{N}$ List))