tasks a-s

Task/Queue-Definition/Erlang/queue-definition.erl

@@ -0,0 +1,13 @@
+-module(fifo).
+-export([new/0, push/2, pop/1, empty/1]).
+
+new() -> {fifo, [], []}.
+
+push({fifo, In, Out}, X) -> {fifo, [X|In], Out}.
+
+pop({fifo, [], []}) -> erlang:error('empty fifo');
+pop({fifo, In, []}) -> pop({fifo, [], lists:reverse(In)});
+pop({fifo, In, [H|T]}) -> {H, {fifo, In, T}}.
+
+empty({fifo, [], []}) -> true;
+empty({fifo, _, _}) -> false.