Programming Flix

Java Collections

Flix has support for conversion from and to Java collections.

In the following, we use the following import aliases:

import java.util.{List => JList}
import java.util.{LinkedList => JLinkedList}
import java.util.{ArrayList => JArrayList}
import java.util.{Set => JSet}
import java.util.{TreeSet => JTreeSet}
import java.util.{Map => JMap}
import java.util.{TreeMap => JTreeMap}

The following functions are available in the Adaptor module:

Flix to Java

The following functions convert Flix collections to Java collections:

///
/// Lists
///
def toList(ma: m[a]): JList \ IO + Aef[m] with Foldable[m]
def toArrayList(ma: m[a]): JArrayList \ IO + Aef[m] with Foldable[m]
def toLinkedList(ma: m[a]): JLinkedList \ IO + Aef[m] with Foldable[m]

///
/// Sets
///
def toSet(ma: m[a]): JSet \ IO + Aef[m] with Order[a], Foldable[m]
def toTreeSet(ma: m[a]): JTreeSet \ IO + Aef[m] with Order[a], Foldable[m]

///
/// Maps
///
def toMap(m: Map[k, v]): JMap \ IO with Order[k]
def toTreeMap(m: Map[k, v]): JTreeMap \ IO with Order[k]

Each function constructs a new collection and copies all its elements into it. Hence each operation takes at least linear time. The result is a normal Java collection (which can be modified).

Java to Flix

The following functions convert Java collections to Flix collections:

/// Lists
def fromList(l: JList): List[a]

/// Sets
def fromSet(l: JSet): Set[a] with Order[a]

/// Maps
def fromMap(m: JMap): Map[k, v] with Order[k]

Each function constructs a new Flix collection from a Java Collection. Hence each operation takes at least linear time. Note that for Set and Map, the Flix collections use the Order[a] instance defined on a. This may not be the same ordering as used by Java.

Warning: Converting Flix and/or Java collections with primitive values requires extra care. In particular, values must be manually boxed or unboxed before any conversion.