diff options
Diffstat (limited to 'system/doc/reference_manual')
| -rw-r--r-- | system/doc/reference_manual/typespec.xml | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/system/doc/reference_manual/typespec.xml b/system/doc/reference_manual/typespec.xml index c5d24a96b5..36ae252b2f 100644 --- a/system/doc/reference_manual/typespec.xml +++ b/system/doc/reference_manual/typespec.xml @@ -132,15 +132,18 @@ | nonempty_list(Type) %% Proper non-empty list Map :: map() %% stands for a map of any size - | #{} %% stands for a map of any size + | #{} %% stands for the empty map | #{PairList} Tuple :: tuple() %% stands for a tuple of any size | {} | {TList} - PairList :: Type => Type - | Type => Type, PairList + PairList :: Pair + | Pair, PairList + + Pair :: Type := Type %% notes a pair that must be present + | Type => Type TList :: Type | Type, TList @@ -170,6 +173,23 @@ The notation <c>[]</c> specifies the singleton type for the empty list. </p> <p> + The general form of maps is <c>#{PairList}</c>. The key types in + <c>PairList</c> are allowed to overlap, and if they do, the leftmost pair + takes precedence. A map value does not belong to this type if contains a key + that is not in <c>PairList</c>. + </p> + <p> + Because it is common to end a map type with <c>any() => any()</c> to denote + that keys that do not belong to any other pair in <c>PairList</c> are + allowed, and may map to any value, the shorhand notation <c>...</c> is + allowed as the last pair of a map type. + </p> + <p> + Notice that the syntactic representation of <c>map()</c> is <c>#{...}</c> + (or <c>#{_ => _}</c>, or <c>#{any() => any()}</c>), not <c>#{}</c>. + The notation <c>#{}</c> specifies the singleton type for the empty map. + </p> + <p> For convenience, the following types are also built-in. They can be thought as predefined aliases for the type unions also shown in the table. @@ -302,12 +322,6 @@ This is described in <seealso marker="#typeinrecords"> Type Information in Record Declarations</seealso>. </p> - <note> - <p>Map types, both <c>map()</c> and <c>#{...}</c>, - are considered experimental during OTP 17.</p> - <p>No type information of maps pairs, only the containing map types, - are used by Dialyzer in OTP 17.</p> - </note> </section> <section> |