Update runtime files

runtime/doc/vim9.txt

@@ -1,4 +1,4 @@
-*vim9.txt*	For Vim version 8.2.  Last change: 2020 Jun 24
+*vim9.txt*	For Vim version 8.2.  Last change: 2020 Jul 10
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -64,16 +64,20 @@ THIS IS STILL UNDER DEVELOPMENT - ANYTHING CAN BREAK - ANYTHING CAN CHANGE
 
 Comments starting with # ~
 
-In Vim script comments normally start with double quote.  That can also be the
-start of a string, thus in many places it cannot be used.  In Vim9 script a
-comment can also start with #.  In Vi this is a command to list text with
-numbers, but you can also use `:number` for that. >
+In Vim script comments start with double quote.  That can also be the start of
+a string, thus in many places it cannot be used.  In Vim9 script a comment
+normally starts with #.  In Vi this is a command to list text with numbers,
+but you can also use `:number` for that. >
 	let count = 0  # number of occurrences
 
 To improve readability there must be a space between the command and the #
 that starts a comment.  Note that #{ is the start of a dictionary, therefore
 it cannot start a comment.
 
+Since Vim9 script allows for line breaks in many places, the double quoted
+comment also cannot be used at the start of a line after an expression.  To
+avoid confusion it is best to only use # comments.
+
 
 Vim9 functions ~
 
@@ -276,10 +280,13 @@ possible just before or after the operator.  For example: >
 
 <							*E1050*
 To make it possible for the operator at the start of the line to be
-recognized, it is required to put a colon before a range.  This will adde
+recognized, it is required to put a colon before a range.  This will add
 "start" and print: >
 	let result = start
 	+ print
+Like this: >
+	let result = start + print
+
 This will assign "start" and print a line: >
 	let result = start
 	:+ print
@@ -291,8 +298,32 @@ arguments: >
 		separator = '-'
 		): string
 
-Note that "enddef" cannot be used at the start of a continuation line, it ends
-the current function.
+Notes:
+- "enddef" cannot be used at the start of a continuation line, it ends the
+  current function.
+- No line break is allowed in the LHS of an assignment.  Specifically when
+  unpacking a list |:let-unpack|. This is OK: >
+  	[var1, var2] =
+		Func()
+<  This does not work: >
+  	[var1,
+	    var2] =
+		Func()
+- No line break is allowed in between arguments of an `:echo`, `:execute` and
+  similar commands.  This is OK: >
+  	echo [1,
+		2] [3,
+			4]
+<  This does not work: >
+  	echo [1, 2]
+		[3, 4]
+- No line break is allowed in the arguments of a lambda, between the "{" and
+  "->".  This is OK: >
+  	filter(list, {k, v ->
+			v > 0})
+<  This does not work: >
+  	filter(list, {k,
+			v -> v > 0})
 
 
 No curly braces expansion ~
@@ -318,7 +349,8 @@ Vim9 script enforces proper use of white space.  This is no longer allowed: >
 	let var =234	" Error!
 There must be white space before and after the "=": >
 	let var = 234	" OK
-White space must also be put before the # that starts a comment: >
+White space must also be put before the # that starts a comment after a
+command: >
 	let var = 234# Error!
 	let var = 234 # OK
 
@@ -479,6 +511,22 @@ prefix.
 			Note that for command line completion of {func} you
 			can prepend "s:" to find script-local functions.
 
+Limitations ~
+
+Local variables will not be visible to string evaluation.  For example: >
+	def EvalString(): list<string>
+	  let list = ['aa', 'bb', 'cc', 'dd']
+	  return range(1, 2)->map('list[v:val]')
+	enddef
+
+The map argument is a string expression, which is evaluated without the
+function scope.  Instead, use a lambda: >
+	def EvalString(): list<string>
+	  let list = ['aa', 'bb', 'cc', 'dd']
+	  return range(1, 2)->map({ _, v -> list[v] })
+	enddef
+
+
 ==============================================================================
 
 4. Types					*vim9-types*