Behaviour Preservation across Code Versions in Erlang

Listing 16

orddict_old.erl.

(1) -spec from_list(List) -> Orddict when

(2)   List:: [Key:: term(), Value:: term()],

(3)   Orddict:: orddict().

(4)

(5) from_list(Pairs) ->

(6)   lists:foldl(

(7)    fun (K,V, D) -> store(K, V, D) end, [], Pairs).

(8)

(9) -spec store(Key, Value, Orddict1) -> Orddict2 when

(10)    Key:: term(),

(11)    Value:: term(),

(12)    Orddict1:: orddict(),

(13)    Orddict2:: orddict().

(14)

(15) store(Key, New, [K,_=E∣Dict]) when Key < K ->

(16)   [Key,New,E∣Dict];

(17) store(Key, New, [K,_=E∣Dict]) when Key > K ->

(18)   [E∣store(Key, New, Dict)];

(19) store(Key, New, [_K,_Old∣Dict]) -> % Key == K

(20)   [Key,New∣Dict];

(21) store(Key, New, []) -> [Key,New].