% <LList T> ::= lNil | lCons(T ({} -> <LList T>))

declare fun {LIter F X} lCons(X fun {$}{LIter F {F X}} end) end

declare fun {LFrom K}{LIter fun {$ N} N+1 end K} end

declare
fun {LTake N LL}
   case N#LL
   of 0#_ then nil
   [] _#lNil then nil
   [] M#lCons(X LT) then X|{LTake M-1 {LT}}
   end
end


declare BST=node("ekran"#"screen"
         node("adapter"#"adapter"
              empty
              node("klawiatura"#"keyboard"
               empty
               empty
              )
             )
         node("komputer"#"computer"
              empty
              node("mysz"#"mouse"
               empty
               empty
              )
             )
        )

fun {Switch BT}
   case BT of
      empty then empty
   [] node(V1#V2 L R) then node(V2#V1 {Switch L} {Switch R})
   end
end

{Inspect {Switch BST}}

fun {Fibonacci}
   local
      fun {Fib A#B}
         lCons(A fun {$}{Fib A+B#A} end)
      end
   in {Fib 0#1}
   end
end

{Browse {LTake 6 {Fibonacci}}}


declare
fun {LDivide LL}
   local
      fun {Divide LL Mod W}
     case LL
     of lNil then lNil
     [] lCons(X LT) then
        case W
        of true then if X mod Mod == 0 then {Divide {LT} Mod W} else
                lCons(X fun{$}{Divide {LT} Mod W}end)end
        [] false then if X mod Mod == 0 then lCons(X fun{$}{Divide {LT} Mod W}end) else
                 {Divide {LT} Mod W} end
        end
     end
      end
   in{Divide LL 3 false}#{Divide LL 3 true}
   end
end



declare
fun {LTakePair LL1#LL2 N1 N2}
   {LTake N1 LL1}#{LTake N2 LL2}
end

{Browse {LTakePair {LDivide {LFrom 1}} 7 7}}

declare
fun {LFoldL LL F Acc N}
   case LL#N
   of _#0  then Acc
   [] lNil#_ then Acc
   [] lCons(X LT)#_ then {LFoldL {LT} F {F Acc X} (N-1)}
   end
end

{Browse {LFoldL {Fibonacci} fun{$Acc X} Acc+X end 0 5}}