Arrays and Lists

Typr provides full support for array and list types across databases that support them.

Database Support

Database	Array Syntax	Element Types
PostgreSQL	text[], int4[]	All scalar types
DuckDB	LIST(varchar), LIST(integer)	All scalar types
MariaDB	-	No array support
Oracle	VARRAY, Nested Table	Via collection types
SQL Server	-	No array support
DB2	-	No array support

PostgreSQL Arrays

PostgreSQL arrays are mapped to Java/Kotlin/Scala arrays:

EmployeeRow

PostgreSQL

JavaKotlinScala

Full file

    Optional<List<String>> skills,
    Optional<List<String>> certifications,

Arrays work seamlessly:

• text[] → List<String>
• int4[] → List<Integer> / List<Int>
• boolean[] → List<Boolean>

DuckDB Lists

DuckDB uses LIST types which map similarly to Java arrays:

EmployeeRow

DuckDB

JavaKotlinScala

Full file

    Optional<List<String>> skills,
    Optional<List<String>> certifications,
    Optional<List<Boolean>> weeklyAvailability,

DuckDB also supports nested types like:

• STRUCT types → Generated as record/data class
• MAP types → See Map Types

Limitations

Multidimensional arrays: PostgreSQL supports multidimensional arrays, but Typr currently generates single-dimension arrays. Nested arrays may be added in the future.

NULL elements: Arrays can contain NULL elements. Use Optional inside the array or check for nulls when processing.