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margnus1/map_adt.erl

Created April 19, 2016 13:10
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Maps and opaque types
Raw
map_adt.erl
-module(map_adt).
-compile(export_all).
-export_type([t/0, t/1, m/0, s/1, sm/1]).
-opaque t() :: #{atom() => integer()}.
-opaque t(A) :: #{A => integer()}.
-opaque m() :: #{t() => integer()}.
-type mt() :: #{t() => integer()}.
-opaque s(K) :: #{K => integer(), integer() => atom()}.
-opaque sm(K) :: #{K := integer(), integer() := atom()}.
-type smt(K) :: #{K := integer(), integer() := atom()}.
-spec t0() -> t().
t0() ->
#{}.
-spec t1() -> t(integer()).
t1() ->
#{3 => 1}.
-spec m0() -> m().
m0() ->
#{#{} => 3}.
-spec mt0() -> mt().
mt0() ->
#{#{} => 3}.
-spec s0() -> s(atom()).
s0() -> #{}.
-spec s1() -> s(atom()). %% No contract breakage (bad warning)
s1() -> #{3 => a}.
-spec s2() -> s(atom() | 3).
s2() -> #{3 => a}. %% Contract breakage
-spec s3() -> s(atom() | 3).
s3() -> #{3 => 5, a => 6, 7 => 8}.
-spec s4() -> s(integer()).
s4() -> #{1 => a}. %% Actual contract breakage (good warning)
-spec s5() -> s(1).
s5() -> #{2 => 3}. %% Contract breakage (not found)
-spec s6() -> s(1).
s6() -> #{1 => 3}.
-spec s7() -> s(integer()).
s7() -> #{1 => 3}.
-spec sm1() -> sm(1). %% No contract breakage (bad warning)
sm1() -> #{1 => 2, 3 => a}.
-spec smt1() -> smt(1).
smt1() -> #{3 => a}. %% Contract breakage
-spec smt2() -> smt(1).
smt2() -> #{1 => a}. %% Contract breakage
-spec smt3() -> smt(1).
smt3() -> #{1 => 1}. %% Slight contract breakage (probably requires better map type)
-spec smt4() -> smt(1).
smt4() -> #{1 => 2, 3 => a}.
Raw
map_use.erl
-module(map_use).
-compile(export_all).
-export_type([t/0, t/1]).
-opaque t() :: #{atom() => integer()}.
-opaque t(A) :: #{A => integer()}.
tt1() ->
A = t0(),
B = t1(),
A =:= B. % never 'true'
-spec t0() -> t().
t0() ->
#{a => 1}.
-spec t1() -> t(integer()).
t1() ->
#{3 => 1}.
adt_tt1() ->
A = adt_t0(),
B = adt_t1(),
A =:= B. % opaque attempt
adt_tt2() ->
A = adt_t0(),
B = adt_t1(),
#{A => 1
,B => 2 % opaque attempt
}.
adt_tt3() ->
A = adt_t0(),
#{A => 1}. %% Should we warn here?
adt_mm1() ->
A = adt_t0(),
M = adt_m0(),
#{A := R} = M, % opaque attempt
R.
%% adt_ms1() ->
%% A = adt_t0(),
%% M = adt_m0(),
%% M#{A}. % opaque attempt
adt_mu1() ->
A = adt_t0(),
M = adt_m0(),
M#{A := 4}. % opaque attempt
adt_mtm1() ->
A = adt_t0(),
M = adt_mt0(),
#{A := R} = M, % opaque attempt
R.
%% adt_mts1() ->
%% A = adt_t0(),
%% M = adt_mt0(),
%% M#{A}. % opaque attempt
adt_mtu1() ->
A = adt_t0(),
M = adt_mt0(),
M#{A := 4}. % opaque attempt
adt_t0() ->
map_adt:t0().
adt_t1() ->
map_adt:t1().
adt_m0() ->
map_adt:m0().
adt_mt0() ->
map_adt:mt0().
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