Document static, make anyint standard

README.md

@@ -2,6 +2,8 @@
 
 Serialization helpers for the Gajumaru.
 
+For an overview of the static serializer, see [this document](doc/static.md).
+
 ## Build
 
     $ rebar3 compile
@@ -30,6 +32,7 @@ how the type information is represented. The fully serialized form is
 produced by the `serialize` functions.
 
 The basic types supported by the encoder are:
+* `integer()`         (`anyint`, code: 246)
 * `neg_integer()`     (`negint`, code: 247)
 * `non_neg_integer()` (`int`   , code: 248)
 * `binary()`          (`binary`, code: 249)
@@ -40,6 +43,9 @@ The basic types supported by the encoder are:
 * `gmser_id:id()`     (`id`    , code: 254)
 * `atom()`            (`label` , code: 255)
 
+(The range of codes is chosen because the `gmser_chain_objects` codes
+range from 10 to 200, and also to stay within 1 byte.)
+
 When encoding `map` types, the map elements are first sorted.
 
 When specifying a map type for template-driven encoding, use 
@@ -122,8 +128,17 @@ to encode as each type in the list, in the specified order, until one matches.
 gmser_dyn:encode_typed(#{alt => [negint,int]}, 5) -> [<<0>>,<<1>>,[<<247>>,<<5>>]]
 gmser_dyn:encode_typed(#{alt => [negint,int]}, 5) -> [<<0>>,<<1>>,[<<248>>,<<5>>]]
 
-gmser_dyn:register_type(246, anyint, #{alt => [negint, int]})
-
 gmser_dyn:encode_typed(anyint,-5) -> [<<0>>,<<1>>,[<<246>>,[<<247>>,<<5>>]]]
 gmser_dyn:encode_typed(anyint,5)  -> [<<0>>,<<1>>,[<<246>>,[<<248>>,<<5>>]]]
 ```
+
+### Notes
+
+Note that `anyint` is a standard type. The static serializer supports only
+positive integers (`int`), as negative numbers are forbidden on-chain.
+For dynamic encoding e.g. in messaging protocols, handling negative numbers can
+be useful, so the `negint` type was added as a dynamic type. To encode a full-range
+integer, the `alt` construct is needed.
+
+(Floats are not supported, as they are non-deterministic. Rationals and fixed-point
+numbers could easily be handled as high-level types, e.g. as `{int,int}`.)