YQL-20520 concat (w/o runtime)

commit_hash:0b092481cfb4813c26c165c17f6d05a9f1f88481

3 files changed, 23 insertions, 0 deletions

diff --git a/yql/essentials/docs/en/builtins/basic.md b/yql/essentials/docs/en/builtins/basic.md
index 994387eaf57..7619c7e9b7f 100644
--- a/yql/essentials/docs/en/builtins/basic.md
+++ b/yql/essentials/docs/en/builtins/basic.md
@@ -90,6 +90,26 @@ SELECT SUBSTRING("abcdefg", 3); -- defg
 SELECT SUBSTRING("abcdefg", NULL, 3); -- abc
 ```
 
+## Concat {#concat}
+
+Concatenate one or more strings.
+
+#### Signature
+
+```yql
+Concat((String|Utf8)[?], ...)->(String|Utf8)[?]
+```
+
+This function is available since version [2025.04](../changelog/2025.04.md).
+If at least one input string is of type `Optional`, then the result is also of type `Optional`.
+If all input strings are of type `Utf8`, then the result is also of type `Utf8`; otherwise, it is `String`.
+If at least one input string is `NULL`, then the result is also of type `NULL`.
+
+#### Examples
+
+```yql
+SELECT Concat("abc", "de", "f"); -- "abcdef"
+```
 
 
 ## FIND {#find}
diff --git a/yql/essentials/docs/en/changelog/2025.04.md b/yql/essentials/docs/en/changelog/2025.04.md
index f6e20c7092d..42652f7a3bf 100644
--- a/yql/essentials/docs/en/changelog/2025.04.md
+++ b/yql/essentials/docs/en/changelog/2025.04.md
@@ -11,6 +11,7 @@ Added linear types.
 * Added `ToDynamicLinear`/`FromDynamicLinear` functions for converting between linear types.
 * Added `LinearType`/`DynamicLinearType` functions for constructing linear types. * Added the `LinearTypeHandle`/`DynamicLinearTypeHandle` functions for constructing linear types during code generation.
 * Added the `LinearItemType` function for retrieving the parameter type from a linear type.
+* Added `Concat` function for string concatenation.
 
 ## Changes in NOT NULL expression
 
diff --git a/yql/essentials/docs/en/syntax/expressions.md b/yql/essentials/docs/en/syntax/expressions.md
index 7d6ceceb9fd..cc8f9bdeb82 100644
--- a/yql/essentials/docs/en/syntax/expressions.md
+++ b/yql/essentials/docs/en/syntax/expressions.md
@@ -10,6 +10,8 @@ As with other binary operators, if the data on either side is `NULL`, the result
 
 Don't confuse this operator with a logical "or": in SQL, it's denoted by the `OR` keyword. It's also not worth doing concatenation using `+`.
 
+There is a similar function for this operator [Concat](../builtins/basic.md#concat), which supports an arbitrary number of arguments.
+
 #### Examples
 
 ```yql