patch 8.2.1408: Vim9: type casting not supported
Problem: Vim9: type casting not supported.
Solution: Introduce type casting.
diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index 8ff7059..7c4a64f 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -640,6 +640,35 @@
{not implemented yet}
+Variable types and type casting *variable-types*
+
+Variables declared in Vim9 script or in a `:def` function have a type, either
+specified explicitly or inferred from the initialization.
+
+Global, buffer, window and tab page variables do not have a specific type, the
+value can be changed at any time, possibly changing the type. Therefore, in
+compiled code the "any" type is assumed.
+
+This can be a problem when the "any" type is undesired and the actual type is
+expected to always be the same. For example, when declaring a list: >
+ let l: list<number> = [1, g:two]
+This will give an error, because "g:two" has type "any". To avoid this, use a
+type cast: >
+ let l: list<number> = [1, <number>g:two]
+< *type-casting*
+The compiled code will then check that "g:two" is a number at runtime and give
+an error if it isn't. This is called type casting.
+
+The syntax of a type cast is: "<" {type} ">". There cannot be white space
+after the "<" or before the ">" (to avoid them being confused with
+smaller-than and bigger-than operators).
+
+The semantics is that, if needed, a runtime type check is performed. The
+value is not actually changed. If you need to change the type, e.g. to change
+it to a string, use the |string()| function. Or use |str2nr()| to convert a
+string to a number.
+
+
Type inference *type-inference*
In general: Whenever the type is clear it can be omitted. For example, when