declare fun {MapP Xs F} case Xs of nil then nil [] X|Xr then thread {F X} end | {Map Xr F} end end {Browse {MapP [1 2 3 4 5] fun {$ X} X*X end}} fun {To N} fun {Help I} if I == N then I|nil else thread I end | thread {Help I+1} end end end in {Help 1} end {Browse {MapP {To 50} fun {$ X} X*X end}}