erl_types: Add a map type representation

The type of a map is represented as a three-tuple {Pairs, DefaultKey,
DefaultValue}. DefaultKey and DefaultValue are types. Pairs is a list of
three-tuples {Key, mandatory | optional, Value}, where Key and Value are
types. All types Key must be singleton, or "known at compile time," as
the EEP put it. Examples:

    #{integer()=>list()}       {[], integer(), list()}
    #{a=>char(), b=>atom()}    {[{a, optional, char()},
                                 {b, optional, atom()}],
                                none(), none()}
    map()                      {[], any(), any()}

A more formal description of the representation and its invariants can
be found in erl_types.erl

Special thanks to Daniel S. McCain (@dsmccain) that co-authored a very
early version of this with me back in April 2014, although only the
singleton type logic remains from that version.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/dialyzer/test/small_SUITE_data/src/maps1.erl b/lib/dialyzer/test/small_SUITE_data/src/maps1.erl
index bb2f66a498..597358d16a 100644
--- a/lib/dialyzer/test/small_SUITE_data/src/maps1.erl
+++ b/lib/dialyzer/test/small_SUITE_data/src/maps1.erl
@@ -21,7 +21,7 @@ recv(Packet, Fun, Chan) ->
   #{id := Can_id, data := Can_data} = P = decode(Packet),
   Fun(P).
 
--spec decode(<<_:64,_:_*8>>) -> #{id => <<_:11>>,timestamp => char()}.
+-spec decode(<<_:64,_:_*8>>) -> #{id => <<_:11>>,timestamp => char(),_ => _}.
 decode(<<_:12, Len:4, Timestamp:16, 0:3, Id:11/bitstring, 0:18,
 	 Data:Len/binary, _/binary>>) ->
   #{id => Id, data => Data, timestamp => Timestamp}.