.. _stdlib_linq_boost:

=====================
Boost module for LINQ
=====================

.. das:module:: linq_boost

The LINQ_BOOST module extends LINQ with pipe-friendly macros using underscore
syntax for inline predicates and selectors. Expressions like
``arr |> _where(_ > 3) |> _select(_ * 2)`` provide concise functional pipelines.

See also :doc:`linq` for the full set of query operations.
See :ref:`tutorial_linq` for a hands-on tutorial.

All functions and symbols are in "linq_boost" module, use require to get access to it.

.. code-block:: das

    require daslib/linq_boost

Example:

.. code-block:: das

    require daslib/linq
        require daslib/linq_boost

        [export]
        def main() {
            var src <- [iterator for (x in range(10)); x]
            var evens <- _where(src, _ % 2 == 0)
            for (v in evens) {
                print("{v} ")
            }
            print("\n")
        }
        // output:
        // 0 2 4 6 8



+++++++++++
Call macros
+++++++++++

.. _call-macro-linq_boost-_order_by:

.. das:attribute:: _order_by

implements _order_by(iterator, expression) shorthand notation
that expands into order_by(iterator, $(_) => expression)
for example::

  each(foo)._order_by(_.id)


.. _call-macro-linq_boost-_union_by:

.. das:attribute:: _union_by

implements _union_by(iterator1, iterator2, expression) shorthand notation
that expands into union_by(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._union_by(each(foo2), _.id)


.. _call-macro-linq_boost-_take_while:

.. das:attribute:: _take_while

implements _take_while(iterator, expression) shorthand notation
that expands into take_while(iterator, $(_) => expression)
for example::

  each(foo)._take_while(_ < 5)


.. _call-macro-linq_boost-_all:

.. das:attribute:: _all

implements _all(iterator, expression) shorthand notation
that expands into all(iterator, $(_) => expression)
for example::

  each(foo)._all(_ < 5)


.. _call-macro-linq_boost-_distinct_by_to_array:

.. das:attribute:: _distinct_by_to_array

implements _distinct_by_to_array(iterator, expression) shorthand notation
that expands into distinct_by_to_array(iterator, $(_) => expression)
for example::

  each(foo)._distinct_by_to_array(_.id)


.. _call-macro-linq_boost-_order_by_to_array:

.. das:attribute:: _order_by_to_array

implements _order_by_to_array(iterator, expression) shorthand notation
that expands into order_by_to_array(iterator, $(_) => expression)
for example::

  each(foo)._order_by_to_array(_.id)


.. _call-macro-linq_boost-_except_by:

.. das:attribute:: _except_by

implements _except_by(iterator1, iterator2, expression) shorthand notation
that expands into except_by(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._except_by(each(foo2), _.id)


.. _call-macro-linq_boost-_min_max_average_by:

.. das:attribute:: _min_max_average_by

implements _min_max_average_by(iterator, expression) shorthand notation
that expands into min_max_average_by(iterator, $(_) => expression)
for example::

  each(foo)._min_max_average_by(_.value)


.. _call-macro-linq_boost-_min_by:

.. das:attribute:: _min_by

implements _min_by(iterator, expression) shorthand notation
that expands into min_by(iterator, $(_) => expression)
for example::

  each(foo)._min_by(_.value)


.. _call-macro-linq_boost-_select_to_array:

.. das:attribute:: _select_to_array

implements _select_to_array(iterator, expression) shorthand notation
that expands into select_to_array(iterator, $(_) => expression)
for example::

  each(foo)._select_to_array(_ * 2)


.. _call-macro-linq_boost-_union_by_to_array:

.. das:attribute:: _union_by_to_array

implements _union_by_to_array(iterator1, iterator2, expression) shorthand notation
that expands into union_by_to_array(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._union_by_to_array(each(foo2), _.id)


.. _call-macro-linq_boost-_unique_by_to_array:

.. das:attribute:: _unique_by_to_array

implements _unique_by_to_array(iterator, expression) shorthand notation
that expands into unique_by_to_array(iterator, $(_) => expression)
for example::

  each(foo)._unique_by_to_array(_.id)


.. _call-macro-linq_boost-_count:

.. das:attribute:: _count

implements _count(iterator, expression) shorthand notation
that expands into count(iterator, $(_) => expression)
for example::

  each(foo)._count(_ > 3)


.. _call-macro-linq_boost-_max_by:

.. das:attribute:: _max_by

implements _max_by(iterator, expression) shorthand notation
that expands into max_by(iterator, $(_) => expression)
for example::

  each(foo)._max_by(_.value)


.. _call-macro-linq_boost-_any:

.. das:attribute:: _any

implements _any(iterator, expression) shorthand notation
that expands into any(iterator, $(_) => expression)
for example::

  each(foo)._any(_ < 5)


.. _call-macro-linq_boost-_except_by_to_array:

.. das:attribute:: _except_by_to_array

implements _except_by_to_array(iterator1, iterator2, expression) shorthand notation
that expands into except_by_to_array(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._except_by_to_array(each(foo2), _.id)


.. _call-macro-linq_boost-_order_by_descending:

.. das:attribute:: _order_by_descending

implements _order_by_descending(iterator, expression) shorthand notation
that expands into order_by_descending(iterator, $(_) => expression)
for example::

  each(foo)._order_by_descending(_.id)


.. _call-macro-linq_boost-_order_by_descending_to_array:

.. das:attribute:: _order_by_descending_to_array

implements _order_by_descending_to_array(iterator, expression) shorthand notation
that expands into order_by_descending_to_array(iterator, $(_) => expression)
for example::

  each(foo)._order_by_descending_to_array(_.id)


.. _call-macro-linq_boost-_distinct_by:

.. das:attribute:: _distinct_by

implements _distinct_by(iterator, expression) shorthand notation
that expands into distinct_by(iterator, $(_) => expression)
for example::

  each(foo)._distinct_by(_.id)


.. _call-macro-linq_boost-_select:

.. das:attribute:: _select

implements _select(iterator, expression) shorthand notation
that expands into select(iterator, $(_) => expression)
for example::

  each(foo)._select(_ * 2)


.. _call-macro-linq_boost-_intersect_by_to_array:

.. das:attribute:: _intersect_by_to_array

implements _intersect_by_to_array(iterator1, iterator2, expression) shorthand notation
that expands into intersect_by_to_array(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._intersect_by_to_array(each(foo2), _.id)


.. _call-macro-linq_boost-_min_max_by:

.. das:attribute:: _min_max_by

implements _min_max_by(iterator, expression) shorthand notation
that expands into min_max_by(iterator, $(_) => expression)
for example::

  each(foo)._min_max_by(_.value)


.. _call-macro-linq_boost-_intersect_by:

.. das:attribute:: _intersect_by

implements _intersect_by(iterator1, iterator2, expression) shorthand notation
that expands into intersect_by(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._intersect_by(each(foo2), _.id)


.. _call-macro-linq_boost-_where_to_array:

.. das:attribute:: _where_to_array

implements _where_to_array(iterator, expression) shorthand notation
that expands into where_to_array(iterator, $(_) => expression)
for example::

  each(foo)._where_to_array(_ < 5)


.. _call-macro-linq_boost-_skip_while:

.. das:attribute:: _skip_while

implements _skip_while(iterator, expression) shorthand notation
that expands into skip_while(iterator, $(_) => expression)
for example::

  each(foo)._skip_while(_ < 5)


.. _call-macro-linq_boost-_where:

.. das:attribute:: _where

implements _where(iterator, expression) shorthand notation
that expands into where_(iterator, $(_) => expression)
for example::

  each(foo)._where(_ < 5)


.. _call-macro-linq_boost-_unique_by:

.. das:attribute:: _unique_by

implements _unique_by(iterator, expression) shorthand notation
that expands into unique_by(iterator, $(_) => expression)
for example::

  each(foo)._unique_by(_.id)


.. _call-macro-linq_boost-_fold:

.. das:attribute:: _fold

implements _fold(expression) that folds LINQ expressions into optimized sequnences
for example::

    _fold(each(foo)._where(_ > 5)._select(_ * 2))

expands into a single comprehension that does all operations in one pass


.. _call-macro-linq_boost-_sequence_equal_by:

.. das:attribute:: _sequence_equal_by

implements _sequence_equal_by(iterator1, iterator2, expression) shorthand notation
that expands into sequence_equal_by(iterator1, iterator2, $(_) => expression)
for example::

  each(foo1)._sequence_equal_by(each(foo2), _.id)