You also have Erlang’s pattern matching at your disposal: decode(<<16#01, Size:8, Payload:Size/binary-unit:8, Rest/binary>>) -> [{field1, Payload}|

You also have Erlang’s pattern matching at your disposal: decode(<<16#01, Size:8, Payload:Size/binary-unit:8, Rest/binary>>) -> [{field1, Payload}|decode(Rest)]; decode(<<16#02, Flags:16, Rest/binary>>) when Flags =:= 1 -> [{field2, true}|decode(Rest)]; decode(<<16#02, Flags:16, Rest/binary>>) -> [{field2, false}|decode(Rest)]. Anything after the when keyword is a guard condition allowing for some manner of positive/negative “look ahead” (Contrived example, but maybe you get the point).