[摘]erlang spec 内置类型

Type :: any()            %% The top type, the set of all Erlang terms.
      | none()           %% The bottom type, contains no terms.
      | pid()
      | port()
      | ref()
      | []               %% nil
      | Atom
      | Binary
      | float()
      | Fun
      | Integer
      | List
      | Tuple
      | Union
      | UserDefined      %% described in Section 2

Union :: Type1 | Type2
Atom :: atom()
      | Erlang_Atom      %% 'foo', 'bar', ...

Binary :: binary()                        %% <<_:_ * 8>>
        | <<>>
        | <<_:Erlang_Integer>>            %% Base size
        | <<_:_*Erlang_Integer>>          %% Unit size
        | <<_:Erlang_Integer, _:_*Erlang_Integer>>

Fun :: fun()                              %% any function
     | fun((...) -> Type)                 %% any arity, returning Type
     | fun(() -> Type)
     | fun((TList) -> Type)
Integer :: integer()
         | Erlang_Integer                 %% ..., -1, 0, 1, ... 42 ...
         | Erlang_Integer..Erlang_Integer %% specifies an integer range

List :: list(Type)                        %% Proper list ([]-terminated)
      | improper_list(Type1, Type2)       %% Type1=contents, Type2=termination
      | maybe_improper_list(Type1, Type2) %% Type1 and Type2 as above

Tuple :: tuple()                          %% stands for a tuple of any size
       | {}
       | {TList}

TList :: Type
       | Type, TList

==========================  =====================================
      Built-in type                   Stands for
==========================  =====================================
``term()``                  ``any()``
``bool()``                  ``'false' | 'true'``
``byte()``                  ``0..255``
``char()``                  ``0..16#10ffff``
``non_neg_integer()``       ``0..``
``pos_integer()``           ``1..``
``neg_integer()``           ``..-1``
``number()``                ``integer() | float()``
``list()``                  ``[any()]``
``maybe_improper_list()``   ``maybe_improper_list(any(), any())``
``maybe_improper_list(T)``  ``maybe_improper_list(T, any())``
``string()``                ``[char()]``
``nonempty_string()``       ``[char(),...]``
``iolist()``                ``maybe_improper_list(``
                                ``char() | binary() |``
                                ``iolist(), binary() | [])``
``module()``                ``atom()``
``mfa()``                   ``{atom(),atom(),byte()}``
``node()``                  ``atom()``
``timeout()``               ``'infinity' | non_neg_integer()``
``no_return()``             ``none()``
==========================  =====================================

摘自：这儿