patch 9.1.0027: Vim is missing a foreach() func

Problem:  Vim is missing a foreach() func
Solution: Implement foreach({expr1}, {expr2}) function,
          which applies {expr2} for each item in {expr1}
          without changing it (Ernie Rael)

closes: #12166

Signed-off-by: Ernie Rael <errael@raelity.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/doc/builtin.txt

@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2024 Jan 05
+*builtin.txt*	For Vim version 9.1.  Last change: 2024 Jan 13
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -198,6 +198,8 @@ foldclosedend({lnum})		Number	last line of fold at {lnum} if closed
 foldlevel({lnum})		Number	fold level at {lnum}
 foldtext()			String	line displayed for closed fold
 foldtextresult({lnum})		String	text for closed fold at {lnum}
+foreach({expr1}, {expr2})	List/Dict/Blob/String
+					for each item in {expr1} call {expr2}
 foreground()			Number	bring the Vim window to the foreground
 fullcommand({name} [, {vim9}])	String	get full command from {name}
 funcref({name} [, {arglist}] [, {dict}])
@@ -2995,6 +2997,45 @@ foldtextresult({lnum})					*foldtextresult()*
 
 		Can also be used as a |method|: >
 			GetLnum()->foldtextresult()
+
+foreach({expr1}, {expr2})					*foreach()*
+		{expr1} must be a |List|, |String|, |Blob| or |Dictionary|.
+		For each item in {expr1} execute {expr2}. {expr1} is not
+		modified; its values may be, as with |:lockvar| 1. *E741*
+		See |map()| and |filter()| to modify {expr1}.
+
+		{expr2} must be a |string| or |Funcref|.
+
+		If {expr2} is a |string|, inside {expr2} |v:val| has the value
+		of the current item.  For a |Dictionary| |v:key| has the key
+		of the current item and for a |List| |v:key| has the index of
+		the current item.  For a |Blob| |v:key| has the index of the
+		current byte. For a |String| |v:key| has the index of the
+		current character.
+		Examples: >
+			call foreach(mylist, 'used[v:val] = true')
+<		This records the items that are in the {expr1} list.
+
+		Note that {expr2} is the result of expression and is then used
+		as a command.  Often it is good to use a |literal-string| to
+		avoid having to double backslashes.
+
+		If {expr2} is a |Funcref| it must take two arguments:
+			1. the key or the index of the current item.
+			2. the value of the current item.
+		With a legacy script lambda you don't get an error if it only
+		accepts one argument, but with a Vim9 lambda you get "E1106:
+		One argument too many", the number of arguments must match.
+		If the function returns a value, it is ignored.
+
+		Returns {expr1} in all cases.
+		When an error is encountered while executing {expr2} no
+		further items in {expr1} are processed.
+		When {expr2} is a Funcref errors inside a function are ignored,
+		unless it was defined with the "abort" flag.
+
+		Can also be used as a |method|: >
+			mylist->foreach(expr2)
 <
 							*foreground()*
 foreground()	Move the Vim window to the foreground.  Useful when sent from

runtime/doc/tags

@@ -5167,6 +5167,7 @@ E738	eval.txt	/*E738*
 E739	builtin.txt	/*E739*
 E74	message.txt	/*E74*
 E740	userfunc.txt	/*E740*
+E741	builtin.txt	/*E741*
 E741	eval.txt	/*E741*
 E742	userfunc.txt	/*E742*
 E743	eval.txt	/*E743*
@@ -7148,6 +7149,7 @@ foldtextresult()	builtin.txt	/*foldtextresult()*
 font-sizes	gui_x11.txt	/*font-sizes*
 fontset	mbyte.txt	/*fontset*
 forced-motion	motion.txt	/*forced-motion*
+foreach()	builtin.txt	/*foreach()*
 foreground()	builtin.txt	/*foreground()*
 fork	os_unix.txt	/*fork*
 form.vim	syntax.txt	/*form.vim*

runtime/doc/usr_41.txt

@@ -1,4 +1,4 @@
-*usr_41.txt*	For Vim version 9.1.  Last change: 2023 May 06
+*usr_41.txt*	For Vim version 9.1.  Last change: 2024 Jan 13
 
 		     VIM USER MANUAL - by Bram Moolenaar
 
@@ -798,6 +798,7 @@ List manipulation:					*list-functions*
 	filter()		remove selected items from a List
 	map()			change each List item
 	mapnew()		make a new List with changed items
+	foreach()		apply function to List items
 	reduce()		reduce a List to a value
 	slice()			take a slice of a List
 	sort()			sort a List
@@ -829,6 +830,7 @@ Dictionary manipulation:				*dict-functions*
 	filter()		remove selected entries from a Dictionary
 	map()			change each Dictionary entry
 	mapnew()		make a new Dictionary with changed items
+	foreach()		apply function to Dictionary items
 	keys()			get List of Dictionary keys
 	values()		get List of Dictionary values
 	items()			get List of Dictionary key-value pairs