diff --git a/docs/api/functions.md b/docs/api/functions.md
index 3108bd6..14f640a 100644
--- a/docs/api/functions.md
+++ b/docs/api/functions.md
@@ -16,68 +16,143 @@ $qb->for('i', '1..100')
     ->sort('i', 'desc')
     ->return('i');
 ```
+## Using unsupported functions
+ArangoDB supports many more functions than those listed below. 
+It is possible to use those by using [rawExpressions](raw-aql.md#raw-expressions).
 
-## ArangoSearch functions
+
+## Supported functions
+The following functions are directly supported in FluentAql.
+
+### ArangoSearch functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
 | analyzer($leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [ANALYZER(expr, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#analyzer) |
-| bm25($doc, $k = null,$b = null) | [BM25(doc, k, b)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#bm25) |
+| bm25($doc, $k, $b) | [BM25(doc, k, b)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#bm25) |
 | boost($leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [BOOST(expr, boost)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#boost) |
-| exists($path,$type = null) | [EXISTS(path)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#exists) |
+| exists($path, $type) | [EXISTS(path)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#exists) |
 | inRange($path, $low, $high, $includeLow, $includeHigh) | [IN_RANGE(path, low, high, includeLow, includeHigh)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#in_range) |
 | levenshteinMatch($path, $target, $distance, $transpositions, $maxTerms, $prefix) | [LEVENSHTEIN_MATCH(path, target, distance, transpositions, maxTerms, prefix)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#levenshtein_match) |
 | like($path, $search)| [LIKE(path, search)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#like) |
 | nGramMatch($path, $target, $threshold, $analyzer) | [NGRAM_MATCH(path, target, threshold, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#ngram_match) |
-| phrase(path, $phrasePart1, $skipTokens1, ... $phrasePartN, $skipTokensN ], $analyzer) | [PHRASE(path, [ phrasePart1, skipTokens1, ... phrasePartN, skipTokensN ], analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#phrase) |
+| phrase(path, $phrasePart1, $skipTokens1, ... $phrasePartN, $skipTokensN, $analyzer) | [PHRASE(path, [ phrasePart1, skipTokens1, ... phrasePartN, skipTokensN ], analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#phrase) |
 | tfidf($doc, $normalize) | [TFIDF(doc, normalize)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#tfidf) |
 
 
-## Array functions
+### Array functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
+| append($array, $values, $unique) | [APPEND(anyArray, values, unique)](https://www.arangodb.com/docs/stable/aql/functions-array.html#append) |
 | count($value)         | [COUNT(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#count) |
 | countDistinct($value) | [COUNT_DISTINCT(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#count) |
 | first($value)         | [FIRST(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#first) | 
+| flatten($array, $depth)| [FLATTEN(anyArray, depth)](https://www.arangodb.com/docs/stable/aql/functions-array.html#flatten) | 
 | last($value)          | [LAST(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#last) | 
 | length($value)        | [LENGTH(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#length) | 
+| shift($array)         | [SHIFT(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#shift) | 
+| union($arrays)        | [UNION(array1, array2, ... arrayN)](https://www.arangodb.com/docs/stable/aql/functions-array.html#union) | 
+| unionDistinct($arrays) | [UNION_DISTINCT(array1, array2, ... arrayN)](https://www.arangodb.com/docs/stable/aql/functions-array.html#union_distinct) | 
+| unique($array)        | [UNIQUE(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-array.html#unique) | 
 
 
-## Date functions
+### Date functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
-| dateNow() | [DATE_NOW()](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_now) | 
-| dateIso8601(numeric|string|DateTime $date) | [DATE_ISO8601(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_iso8601) | 
-| dateTimestamp(numeric|string|DateTime $date) | [DATE_TIMESTAMP(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_timestamp) | 
-| dateYear($date) | [DATE_YEAR(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_year) | 
-| dateMonth($date) | [DATE_MONTH(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_month) | 
+| dateCompare($date1, $date2, $unitRangeStart, $unitRangeEnd) | [DATE_COMPARE(date1, date2, unitRangeStart, unitRangeEnd)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_compare) | 
 | dateDay($date) | [DATE_DAY(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_day) | 
+| dateFormat($date, $format) | [DATE_FORMAT(date, format)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_format) | 
 | dateHour($date) | [DATE_HOUR(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_hour) | 
+| dateIso8601($date) | [DATE_ISO8601(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_iso8601) | 
+| dateLocalToUtc($date, $timezone, $zoneInfo) | [DATE_LOCALTOUTC(date, timezone, zoneinfo)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_localtoutc) | 
+| dateMonth($date) | [DATE_MONTH(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_month) | 
+| dateNow() | [DATE_NOW()](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_now) | 
+| dateMillisecond($date) | [DATE_MILLISECOND(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_millisecond) | 
 | dateMinute($date) | [DATE_MINUTE(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_minute) | 
+| dateRound($date, $amount, $unit) | [DATE_ROUND(date, amount, unit)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_round) | 
 | dateSecond($date) | [DATE_SECOND(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_second) | 
-| dateMillisecond($date) | [DATE_MILLISECOND(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_millisecond) | 
-| dateFormat($date, $format) | [DATE_FORMAT(date, format)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_format) | 
+| dateTimestamp($date) | [DATE_TIMESTAMP(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_timestamp) | 
+| dateTrunc($date, $unit) | [DATE_TRUNC(date, unit)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_trunc) | 
+| dateUtcToLocal($date, $timezone, $zoneInfo) | [DATE_UTCTOLOCAL(date, timezone, zoneinfo)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_utctolocal) | 
+| dateYear($date) | [DATE_YEAR(date)](https://www.arangodb.com/docs/stable/aql/functions-date.html#date_year) | 
 
-## GEO functions
+
+### Document functions
+| Description           | AQL Function |
+| :-------------------- | :-------------------------------------------------------------------------------------------- |
+| attributes($document, $removeInternal, $sort) | [ATTRIBUTES(document, removeInternal, sort)](https://www.arangodb.com/docs/stable/aql/functions-document.html#attributes) | 
+| keepAttributes($document, $attributes) | [KEEP(document, attributeName1, attributeName2, ... attributeNameN)](https://www.arangodb.com/docs/stable/aql/functions-document.html#keep) | 
+| matches($document, $examples,$returnIndex) | [MATCHES(document, examples, returnIndex)](https://www.arangodb.com/docs/stable/aql/functions-document.html#matches) | 
+| merge(...$documents) | [MERGE(...documents)](https://www.arangodb.com/docs/stable/aql/functions-document.html#merge) | 
+| parseIdentifier($documentHandle) | [PARSE_IDENTIFIER(documentHandle)](https://www.arangodb.com/docs/stable/aql/functions-document.html#parse_identifier) | 
+| unset($document, $attributes) | [UNSET(document, ...attributeName)](https://www.arangodb.com/docs/stable/aql/functions-document.html#unset) | 
+
+
+### GEO functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
 | distance($latitude1, $longitude1, $latitude2, $longitude2) | [DISTANCE(latitude1, longitude1, latitude2, longitude2)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#distance) | 
+| geoArea($geoJson, $ellipsoid) | [GEO_AREA(geoJson, ellipsoid)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_area) | 
+| geoContains($geoJsonA, $geoJsonB) | [GEO_AREA(GEO_CONTAINS(geoJsonA, geoJsonB)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_contains) | 
+| geoDistance($geoJsonA, $geoJsonB, $ellipsoid) | [GEO_DISTANCE(geoJsonA, geoJsonB, ellipsoid)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_distance) | 
+| geoEquals($geoJsonA, $geoJsonB) | [GEO_EQUALS(geoJsonA, geoJsonB)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_equals) | 
+| geoIntersects($geoJsonA, $geoJsonB) | [GEO_INTERSECTS(geoJsonA, geoJsonB)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_intersects) | 
+| geoInRange($geoJsonA, $geoJsonB, $low, $high, $includeLow, $includeHigh) | [GEO_IN_RANGE(geoJsonA, geoJsonB, low, high, includeLow, includeHigh)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_in_range) | 
+| geoLineString($points) | [GEO_LINESTRING(points)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_linestring) | 
+| geoMultiLineString($points) | [GEO_MULTILINESTRING(points)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_multilinestring) | 
+| geoMultiPoint($points) | [GEO_MULTIPOINT(points)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_multipoint) | 
+| geoPoint($longitude, $latitude) | [GEO_POINT(longitude, latitude)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_point) | 
+| geoPolygon($points) | [GEO_POLYGON(points)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_polygon) | 
+| geoMultiPolygon($points) | [GEO_MULTIPOLYGON(points)](https://www.arangodb.com/docs/stable/aql/functions-geo.html#geo_multipolygon) | 
+
 
-## Miscellaneous functions
+### Miscellaneous functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
-| document($collection, $id = null) | [DOCUMENT(collection, id)](https://www.arangodb.com/docs/stable/aql/functions-miscellaneous.html#document) | 
+| document($collection, $id) | [DOCUMENT(collection, id)](https://www.arangodb.com/docs/stable/aql/functions-miscellaneous.html#document) | 
+| firstDocument(...$arguments) | [FIRST_DOCUMENT(alternative, ...)](https://www.arangodb.com/docs/stable/aql/functions-miscellaneous.html#first_document) | 
 
-## Numeric functions
+
+### Numeric functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
 | average($value) | [AVERAGE(numArray](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#average) | 
 | avg($value) | [AVG(numArray](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#average) | 
+| ceil($value) | [CEIL(value)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#ceil) | 
+| floor($value) | [FLOOR(value)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#floor) | 
 | max($value) | [MAX(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#max) | 
 | min($value) | [MIN(anyArray)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#min) | 
+| product($array) | [PRODUCT(numArray)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#min) | 
 | rand() | [RAND()](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#rand) | 
+| range($start, $stop, $step) | [RANGE(start, stop, step)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#range) | 
+| round($value) | [ROUND(value)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#round) | 
 | sum($value) | [SUM(numArray)](https://www.arangodb.com/docs/stable/aql/functions-numeric.html#sum) | 
 
-## String functions
+
+### String functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
 | concat(...$arguments) | [CONCAT(value1, value2, ... valueN)](https://www.arangodb.com/docs/stable/aql/functions-string.html#concat) | 
+| concatSeparator($separator, $values) | [CONCAT_SEPARATOR(separator, value1, value2, ... valueN)](https://www.arangodb.com/docs/stable/aql/functions-string.html#concat_separator) | 
+| levenshteinDistance($value1, $value2) | [LEVENSHTEIN_DISTANCE(value1, value2)](https://www.arangodb.com/docs/stable/aql/functions-string.html#levenshtein_distance) | 
+| lower($value)| [LOWER(value)](https://www.arangodb.com/docs/stable/aql/functions-string.html#lower) | 
+| regexMatches($text, $regex, $caseInsensitive)| [REGEX_MATCHES(text, regex, caseInsensitive)](https://www.arangodb.com/docs/stable/aql/functions-string.html#regex_matches) | 
+| regexReplace($text, $regex, $replacement, $caseInsensitive)| [REGEX_REPLACE(text, search, replacement, caseInsensitive)](https://www.arangodb.com/docs/stable/aql/functions-string.html#regex_replace) | 
+| regexSplit($text, $splitExpression, $caseInsensitive, $limit)| [REGEX_SPLIT(text, splitExpression, caseInsensitive, limit)](https://www.arangodb.com/docs/stable/aql/functions-string.html#regex_split) | 
+| regexTest($text, $search, $caseInsensitive)| [REGEX_TEST(text, search, caseInsensitive)](https://www.arangodb.com/docs/stable/aql/functions-string.html#regex_test) | 
+| split($value, $separator, $limit)| [SPLIT(value, separator, limit)](https://www.arangodb.com/docs/stable/aql/functions-string.html#split) | 
+| substitute($text, $search, $replace, $limit)| [SUBSTITUTE(value, search, replace, limit)](https://www.arangodb.com/docs/stable/aql/functions-string.html#substitute) | 
+| substring($value, $offset, $length)| [SUBSTRING(value, offset, length)](https://www.arangodb.com/docs/stable/aql/functions-string.html#substitute) | 
+| tokens($input, $analyzer)| [TOKENS(input, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-string.html#tokens) | 
+| trim($value, $type)| [TRIM(value, type)](https://www.arangodb.com/docs/stable/aql/functions-string.html#trim) | 
+| upper($value)| [UPPER(value)](https://www.arangodb.com/docs/stable/aql/functions-string.html#upper) | 
+| uuid()| [UUID()](https://www.arangodb.com/docs/stable/aql/functions-string.html#uuid) | 
+
+
+### Type functions
+| Description           | AQL Function |
+| :-------------------- | :-------------------------------------------------------------------------------------------- |
+| toArray($value) | [TO_ARRAY(value)](https://www.arangodb.com/docs/stable/aql/functions-type-cast.html#to_array) | 
+| toBool($value) | [TO_BOOL(value)](https://www.arangodb.com/docs/stable/aql/functions-type-cast.html#to_bool) | 
+| tolist($value) | [TO_LIST(value)](https://www.arangodb.com/docs/stable/aql/functions-type-cast.html#to_list) | 
+| toNumber($value) | [TO_NUMBER(value)](https://www.arangodb.com/docs/stable/aql/functions-type-cast.html#to_number) | 
+| toString($value) | [TO_STRING(value)](https://www.arangodb.com/docs/stable/aql/functions-type-cast.html#to_string) | 
diff --git a/src/AQL/HasArrayFunctions.php b/src/AQL/HasArrayFunctions.php
index 8a7fe0a..b3ce483 100644
--- a/src/AQL/HasArrayFunctions.php
+++ b/src/AQL/HasArrayFunctions.php
@@ -137,6 +137,34 @@ public function shift(mixed $array): FunctionExpression
         return new FunctionExpression('SHIFT', [$array]);
     }
 
+    /**
+     * Return the union of all arrays specified.
+     *
+     * @link https://www.arangodb.com/docs/stable/aql/functions-array.html#union
+     *
+     * @param array<mixed>|Expression|QueryBuilder $arrays
+     * @return FunctionExpression
+     */
+    public function union(
+        array|Expression|QueryBuilder ...$arrays
+    ): FunctionExpression {
+        return new FunctionExpression('UNION', [$arrays]);
+    }
+
+    /**
+     * Return the union of distinct values of all arrays specified.
+     *
+     * @link https://www.arangodb.com/docs/stable/aql/functions-array.html#union_distinct
+     *
+     * @param array<mixed>|Expression|QueryBuilder $arrays
+     * @return FunctionExpression
+     */
+    public function unionDistinct(
+        array|Expression|QueryBuilder ...$arrays
+    ): FunctionExpression {
+        return new FunctionExpression('UNION_DISTINCT', [$arrays]);
+    }
+
     /**
      * Return all unique elements in an Array.
      *
diff --git a/src/AQL/HasStringFunctions.php b/src/AQL/HasStringFunctions.php
index 71ad0cb..f316842 100644
--- a/src/AQL/HasStringFunctions.php
+++ b/src/AQL/HasStringFunctions.php
@@ -4,7 +4,9 @@
 
 namespace LaravelFreelancerNL\FluentAQL\AQL;
 
+use LaravelFreelancerNL\FluentAQL\Expressions\Expression;
 use LaravelFreelancerNL\FluentAQL\Expressions\FunctionExpression;
+use LaravelFreelancerNL\FluentAQL\QueryBuilder;
 
 /**
  * Geo AQL functions.
@@ -28,10 +30,17 @@ public function concat(
      * Concatenate the strings passed as arguments value1 to valueN using the separator string.
      *
      * @link https://www.arangodb.com/docs/stable/aql/functions-string.html#concat_separator
+     *
+     * @param string|Expression|QueryBuilder $separator
+     * @param array<int, string|array<string>|Expression|QueryBuilder> ...$values
+     * @return FunctionExpression
      */
     public function concatSeparator(
-        string|object ...$arguments
+        string|Expression|QueryBuilder $separator,
+        string|array|Expression|QueryBuilder ...$values
     ): FunctionExpression {
+        $arguments = array_merge([$separator], $values);
+
         return new FunctionExpression('CONCAT_SEPARATOR', $arguments);
     }
 
diff --git a/src/Traits/NormalizesArrayFunctions.php b/src/Traits/NormalizesArrayFunctions.php
index 56f4a6e..294aed5 100644
--- a/src/Traits/NormalizesArrayFunctions.php
+++ b/src/Traits/NormalizesArrayFunctions.php
@@ -74,6 +74,16 @@ protected function normalizeShift(QueryBuilder $queryBuilder): void
         );
     }
 
+    protected function normalizeUnion(QueryBuilder $queryBuilder): void
+    {
+        $this->normalizeArrays($queryBuilder);
+    }
+
+    protected function normalizeUnionDistinct(QueryBuilder $queryBuilder): void
+    {
+        $this->normalizeArrays($queryBuilder);
+    }
+
     protected function normalizeUnique(QueryBuilder $queryBuilder): void
     {
         $this->parameters[0] = $queryBuilder->normalizeArgument(
diff --git a/tests/Unit/AQL/ArrayFunctionsTest.php b/tests/Unit/AQL/ArrayFunctionsTest.php
index f6ee5b2..4ebf19a 100644
--- a/tests/Unit/AQL/ArrayFunctionsTest.php
+++ b/tests/Unit/AQL/ArrayFunctionsTest.php
@@ -74,6 +74,29 @@ public function testShift()
         self::assertEquals('RETURN SHIFT([1,3,4,5])', $qb->get()->query);
     }
 
+    public function testUnion()
+    {
+        $qb = new QueryBuilder();
+        $qb->return($qb->union([ 1, 2, 3 ], [ 1, 2 ]));
+
+        self::assertSame(
+            'RETURN UNION([[1,2,3],[1,2]])',
+            $qb->get()->query
+        );
+    }
+
+    public function testUnionDistinct()
+    {
+        $qb = new QueryBuilder();
+        $qb->return($qb->unionDistinct([ 1, 2, 3 ], [ 1, 2 ]));
+
+        self::assertSame(
+            'RETURN UNION_DISTINCT([[1,2,3],[1,2]])',
+            $qb->get()->query
+        );
+    }
+
+
     public function testUnique()
     {
         $qb = new QueryBuilder();