# Lists

Cypher has comprehensive support for lists.

 Information regarding operators such as list concatenation (`+`), element existence checking (`IN`) and access (`[]`) can be found here. The behavior of the `IN` and `[]` operators with respect to `null` is detailed here.

## 1. Lists in general

A literal list is created by using brackets and separating the elements in the list with commas.

Query
``RETURN [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] AS list``
Table 1. Result
list

`[0,1,2,3,4,5,6,7,8,9]`

1 row

In our examples, we’ll use the `range` function. It gives you a list containing all numbers between given start and end numbers. Range is inclusive in both ends.

To access individual elements in the list, we use the square brackets again. This will extract from the start index and up to but not including the end index.

Query
``RETURN range(0, 10)``
Table 2. Result
range(0, 10)

`3`

1 row

You can also use negative numbers, to start from the end of the list instead.

Query
``RETURN range(0, 10)[-3]``
Table 3. Result
range(0, 10)[-3]

`8`

1 row

Finally, you can use ranges inside the brackets to return ranges of the list.

Query
``RETURN range(0, 10)[0..3]``
Table 4. Result
range(0, 10)[0..3]

`[0,1,2]`

1 row

Query
``RETURN range(0, 10)[0..-5]``
Table 5. Result
range(0, 10)[0..-5]

`[0,1,2,3,4,5]`

1 row

Query
``RETURN range(0, 10)[-5..]``
Table 6. Result
range(0, 10)[-5..]

`[6,7,8,9,10]`

1 row

Query
``RETURN range(0, 10)[..4]``
Table 7. Result
range(0, 10)[..4]

`[0,1,2,3]`

1 row

 Out-of-bound slices are simply truncated, but out-of-bound single elements return `null`.
Query
``RETURN range(0, 10)``
Table 8. Result
range(0, 10)

`<null>`

1 row

Query
``RETURN range(0, 10)[5..15]``
Table 9. Result
range(0, 10)[5..15]

`[5,6,7,8,9,10]`

1 row

You can get the `size` of a list as follows:

Query
``RETURN size(range(0, 10)[0..3])``
Table 10. Result
size(range(0, 10)[0..3])

`3`

1 row

## 2. List comprehension

List comprehension is a syntactic construct available in Cypher for creating a list based on existing lists. It follows the form of the mathematical set-builder notation (set comprehension) instead of the use of map and filter functions.

Query
``RETURN [x IN range(0,10) WHERE x % 2 = 0 | x^3] AS result``
Table 11. Result
result

`[0.0,8.0,64.0,216.0,512.0,1000.0]`

1 row

Either the `WHERE` part, or the expression, can be omitted, if you only want to filter or map respectively.

Query
``RETURN [x IN range(0,10) WHERE x % 2 = 0] AS result``
Table 12. Result
result

`[0,2,4,6,8,10]`

1 row

Query
``RETURN [x IN range(0,10)| x^3] AS result``
Table 13. Result
result

`[0.0,1.0,8.0,27.0,64.0,125.0,216.0,343.0,512.0,729.0,1000.0]`

1 row

## 3. Pattern comprehension

Pattern comprehension is a syntactic construct available in Cypher for creating a list based on matchings of a pattern. A pattern comprehension will match the specified pattern just like a normal `MATCH` clause, with predicates just like a normal `WHERE` clause, but will yield a custom projection as specified.

The following graph is used for the example below: Query
``````MATCH (a:Person { name: 'Keanu Reeves' })
RETURN [(a)-->(b) WHERE b:Movie | b.released] AS years``````
Table 14. Result
years

`[1997,2003,2003,2000,1999,2003,1995]`

1 row

The whole predicate, including the `WHERE` keyword, is optional and may be omitted.