fun map f [] = []  | map f (x :: xs) = f x :: map f xs; map (fn n => n+1) [1,2,3]; infix 5 ++; fun [] ++ ys = ys  | (x :: xs) ++ ys = x :: (xs ++ ys); [1,2,3] ++ [4,5,6]; fun reverse xs =  let    infix -->    fun [] --> ys = ys      | (x::xs) --> ys = xs --> (x::ys)  in xs --> [] end; reverse [1,2,3,4];reverse [true,false]; infix 3 o;fun (f o g) x = f(g x); let     val I = reverse o reversein    I [1,2,3]end; val zl = [(1,true),(2,false),(3,true)]; fun fst (x,_) = x;fun snd (_,y) = y; map fst zl; fun split [] = ([],[])  | split ((x,y) :: rest) =      let val (xs,ys) = split rest in        (x :: xs, y :: ys)      end; split zl; fun member a [] = false  | member a (x::xs) =      case a=x        of true => true         | false => member a xs;member 3 [1,2,3,4];member 3 [1,2];