all tasks

Task/Stack/Erlang/stack-1.erl

@@ -0,0 +1,13 @@
+-module(stack).
+-export([empty/1, new/0, pop/1, push/2, top/1]).
+
+new() -> [].
+
+empty([]) -> true;
+empty(_) -> false.
+
+pop([H|T]) -> {H,T}.
+
+push(H,T) -> [H|T].
+
+top([H|_]) -> H.

Task/Stack/Erlang/stack-2.erl

@@ -0,0 +1,14 @@
+1> c(stack).
+{ok,stack}
+2> Stack = stack:new().
+[]
+3> NewStack = lists:foldl(fun stack:push/2, Stack, [1,2,3,4,5]).
+[5,4,3,2,1]
+4> stack:top(NewStack).
+5
+5> {Popped, PoppedStack} = stack:pop(NewStack).
+{5,[4,3,2,1]}
+6> stack:empty(NewStack).
+false
+7> stack:empty(stack:new()).
+true