The document discusses the Scala collections API, highlighting its rich library capabilities for manipulating various data structures like lists, sets, and hash maps. It provides a model case demonstrating how to sort a list of products, transform their names to uppercase, retrieve unique category names, group products by the initial letter of their names, and create tuples of product and category names. The document includes practical examples of using higher-order functions for these operations.

1. Scala:
collec)ons

2. The
collec)ons
API
• Very
rich
library
for
manipula)ng
collec)ons
of
objects
• Great
examples
of
higher
order
func)ons
• The
usual
suspects:
Lists,
Sets,
Hash
Maps.
• But
also:
Streams,
Buffers,
Arrays,
Trees

3. Let's
take
this
model
case class Category(
name: String,
parent: Option[Category])
case class Product(
name: String,
description: String,
category: Category)

4. Given
a
list
of
products
• Sort
them
by
name
• Get
their
names
in
uppercase
• Get
the
set
of
categories
(no
repeats)
• Group
them
by
the
ini)al
of
their
names
• Return
a
tuple
with
the
product
and
category
names

5. Sor)ng
case class Product(
name: String,
description: String,
category: Category)
val products = List( ... ) // List of products
// Sort by name
products.sortBy(_.name)

6. Mapping
// Get their names in uppercase
val names: List[String] =
products.map(_.name.toUpperCase)

7. Extrac)ng
// Get category name set
val catNames : Set[String] =
products.map(_.category.name).toSet

8. Grouping
// Group by the initial of their names
val grouped : Map[Char, List[Product]] =
products.groupBy(_.name.head)

9. More
Mapping
// Create tuples of product and category
names
val pairs : Tuple2[String,String] =
for {
product <- products
category = product.category
} yield (product.name, category.name)