# [root] · Rell standard library · Chromia Docs (concept) > Global namespace containing types and functions accessible without any namespace prefix. Types big_integer An immutable signed integer type, supporting ext Source: https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/ PACKAGE # [root] On this page * [Types](#types) * [Functions](#functions) * [Aliases](#aliases) Global namespace containing types and functions accessible without any namespace prefix. ## Types [big\_integer](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/big_integer/) : An immutable signed integer type, supporting extremely large values (upwards of 100,000 decimal digits). [boolean](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/boolean/) : A data type with two possible values: true and false. [byte\_array](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/byte_array/) : An array of bytes. This type is immutable. [collection](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/collection/) : A generic type for mutable ordered collections of elements. Subtype of iterable. Supports many [decimal](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/decimal/) : A real number data type with high precision. [entity](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/entity/) : Parent of all entity types. An entity is a data structure that resides in the SQL database. [enum](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/enum/) : An enum is a set of member constants who share a type. [gtv](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/gtv/) : Generic Transfer Value (GTV) is a data type for the serialization and transfer of structured data, much [gtx\_operation](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/gtx_operation/) [gtx\_transaction](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/gtx_transaction/) [gtx\_transaction\_body](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/gtx_transaction_body/) [immutable\_mirror\_struct](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/immutable_mirror_struct/) [integer](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/integer/) : A 64-bit signed integer type, ranging from -2^63 to (2^63)-1, supporting a standard [iterable](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/iterable/) : A generic type for sequences that can be iterated over, such as collections, ranges and maps. [json](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/json/) : A JSON (JavaScript Object Notation) datatype. [list](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/list/) : Represents a mutable array list. Subtype of collection. [map](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/map/) : A mutable map from keys of type K to values of type V, where K is immutable, and V may be either [map\_entry](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/map_entry/) : A supertype of all two-element tuples (K, V) (with named and unnamed fields), where K is an [mirror\_struct](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/mirror_struct/) [mutable\_mirror\_struct](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/mutable_mirror_struct/) [null\_ext](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/null_ext/) [object](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/object/) : Parent of all object types. An object is a singleton data structure that resides in the SQL database. [operation](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/operation/) [range](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/range/) : A range of integer values. Ranges represent arithmetic sequences with defined start and end points, and [rowid](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/rowid/) : The primary key of a database record. [set](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/set/) : A mutable set of elements of type T, where T is immutable. Subtype of collection. Implemented [struct](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/struct/) [text](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/text/) : An immutable character string data type. [try\_call\_result](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/try_call_result/) : Type representing the result of a function call that may have thrown a require exception. [unit](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/unit/) : A type with no member values, much like void in other languages. [virtual](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/virtual/) [virtual\_collection](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/virtual_collection/) [virtual\_list](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/virtual_list/) [virtual\_map](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/virtual_map/) [virtual\_set](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/virtual_set/) ## Functions [abs](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/abs/) : Returns the absolute value of a integer value; i.e. the value itself if it's positive or its negation if [empty](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/empty/) : Checks if a value is absent, i.e. null or empty. [eth\_ecrecover](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/eth_ecrecover/) : Compute an Ethererum public key from a signature and a hash. [exists](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/exists/) : Checks if a value is present, i.e. not null and not empty. [is\_signer](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/is_signer/) : Check if a given public key is a signer of the current transaction; i.e. if it's in the list of signers [keccak256](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/keccak256/) : Compute the Keccak256 digest (hash) of the given byte array. [log](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/log/) : Prints the given value(s) to the log, with a timestamp, and then terminates the line. [max](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/max/) : Returns the greater of two integer values; i.e. a if a > b, or b otherwise. [min](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/min/) : Returns the lesser of two integer values; i.e. a if a < b, or b otherwise. [print](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/print/) : Prints the given value(s) to STDOUT, and then terminates the line. [require](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/require/) : Asserts a boolean condition. [requireNotEmpty](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/require-not-empty/) : Asserts that a list is non-null and non-empty. [require\_not\_empty](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/require_not_empty/) : Asserts that a list is non-null and non-empty. [sha256](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/sha256/) : Compute the SHA-256 digest (hash) of the given byte array. [try\_call](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/try_call/) : Safely call a function that may fail (i.e. that may throw an exception). [try\_call\_catch](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/try_call_catch/) : Safely call a function that may fail (i.e. that may throw an exception), returning a result that can be [verify\_signature](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/verify_signature/) : Verify a signature against a message and public key. ## Aliases [GTXValue](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/-g-t-x-value/) : Generic Transfer Value (GTV) is a data type for the serialization and transfer of structured data, much [name](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/name/) : An immutable character string data type. [pubkey](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/pubkey/) : An array of bytes. This type is immutable. [timestamp](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/timestamp/) : A 64-bit signed integer type, ranging from -2^63 to (2^63)-1, supporting a standard [View this page on docs.chromia.com](https://docs.chromia.com/pages/rell-stdlib/-rell%20-system%20-library/%5Broot%5D/index.html)Generated API reference, mirrored from the live docs