scala presentatie
DESCRIPTION
Short (1hr) introduction to Scala Programming given to Topicus at 23rd of september, 2014. Accompanied by github projects: https://github.com/gedejong/overpascala https://github.com/gedejong/pollardRhoTRANSCRIPT
ScalaIntroductie voor Java (7) kenners
Martin Oderski
• Statically typed
• Statically typed
• Type inference
• Statically typed
• Type inference
• Functional / OOP
• Statically typed
• Type inference
• Functional / OOP
• Compiled naar JVM bytecode
• Statically typed
• Type inference
• Functional / OOP
• Compiled naar JVM bytecode
• én .NET
• Statically typed
• Type inference
• Functional / OOP
• Compiled naar JVM bytecode
• én .NET
• én Javascript (scalajs)
Static vs. Dynamic
Type chaos
Type chaos<K, V> List<K> keysAsList(HashMap<K, V> aMap) {
List<K> result = new LinkedList<K>();
for (K key : aMap.keySet()) {
result.add(key);
}
return result;
}
Implicit types
Implicit types
def keysAsList[K, V](m: Map[K, V]) =m.keySet.toList
Alles is een object
Overpass Query Model
Overpass Query Model
Node
Overpass Query Model
Node
Way
Overpass Query Model
Node
Relation
Way
node["addr:city"="Deventer"]["addr:housenumber"="25"]["addr:street"="Singel"];out
node["addr:city"="Deventer"]["addr:housenumber"="25"]["addr:street"="Singel"];out
Node( "addr:city" === "Deventer" and "addr:housenumber" === "25" and "addr:street" === "Singel") | OutStatement
node(2678759904);way(around: 1000);(rel(bw)["route"="bicycle"]["type"="route"];way(r);node(w););out
node(2678759904);way(around: 1000);(rel(bw)["route"="bicycle"]["type"="route"];way(r);node(w););out
Node(Id(2678759904)) | Way(Around(1.kilo[metre])) | Union( Relation(isPartOf(Ways) and "route" === "bicycle" and "type" === "route") | Way(containedIn(Relations)) | Node(containedIn(Ways)) ) | OutStatement)
sealed trait Statement
sealed trait Statement!case object OutStatement extends Statement
sealed trait Statement!case object OutStatement extends Statement !sealed trait PipeableStatement extends Statement { def |(other: Statement) = PipedStatement(this, other) def into(variable: String) = IntoStatement(this, variable) }
sealed trait Statement!case object OutStatement extends Statement !sealed trait PipeableStatement extends Statement { def |(other: Statement) = PipedStatement(this, other) def into(variable: String) = IntoStatement(this, variable) }!case class PipedStatement(left: Statement, right: Statement) extends PipeableStatement !case class IntoStatement(s: Statement, variable: String) extends PipeableStatement
Pimp my types
Pimp my types implicit class PimpedStringClause(str: String) { def ===(other: String) = Eq(str, other) def !==(other: String) = Neq(str, other) def ==~(other: String) = Regex(str, other) def !=~(other: String) = Regex(str, other) }
Pimp my types implicit class PimpedStringClause(str: String) { def ===(other: String) = Eq(str, other) def !==(other: String) = Neq(str, other) def ==~(other: String) = Regex(str, other) def !=~(other: String) = Regex(str, other) }
val str = “addr:street” new PimpedStringClause(str).===(“Singel 25”)
Pimp my types implicit class PimpedStringClause(str: String) { def ===(other: String) = Eq(str, other) def !==(other: String) = Neq(str, other) def ==~(other: String) = Regex(str, other) def !=~(other: String) = Regex(str, other) }
val str = “addr:street” new PimpedStringClause(str).===(“Singel 25”)
Eq( “addr:street”, “Singel 25”)
Pimp my types implicit class PimpedStringClause(str: String) { def ===(other: String) = Eq(str, other) def !==(other: String) = Neq(str, other) def ==~(other: String) = Regex(str, other) def !=~(other: String) = Regex(str, other) }
val str = “addr:street” new PimpedStringClause(str).===(“Singel 25”)
str.===(“Singel 25”)
Eq( “addr:street”, “Singel 25”)
Pimp my types implicit class PimpedStringClause(str: String) { def ===(other: String) = Eq(str, other) def !==(other: String) = Neq(str, other) def ==~(other: String) = Regex(str, other) def !=~(other: String) = Regex(str, other) }
val str = “addr:street” new PimpedStringClause(str).===(“Singel 25”)
str.===(“Singel 25”)
str === “Singel 25”
Eq( “addr:street”, “Singel 25”)
Pattern matchingdef ClauseShows[S <: Clause]: Show[S] = shows { case Id(id) ⇒ s"($id)"
case Eq(tag, value) ⇒ s"""["$tag"="$value"]"""
case HasKey(tag) ⇒ """["$tag"]"""
case Regex(tag, value) ⇒ s"""["$tag"~"$value"]"""
… }
Map, flatmap en filter
Type-safe DSLs
Type-safe DSLs
val avg: Option[Float] = from(grades)(g => where(g.subjectId === mathId) compute(avg(g.scoreInPercentage)) )
Running Demo: OpenStreetMaps en
Buienradar
Buienradar APIhttp://gps.buienradar.nl/getrr.php?
lat=52.2560148&lon=6.160242
000|17:35 040|17:40 000|17:45 000|17:50 000|17:55 000|18:00 000|18:05 063|18:10 000|18:15 000|18:20 000|18:25 000|18:30 000|18:35 000|18:40 000|18:45 000|18:50 000|18:55 000|19:00 000|19:05 000|19:10 000|19:15 000|19:20 000|
19:25 000|19:30 000|19:35
GET
• Actors
• Actors
• Scalaz
• Actors
• Scalaz
• Higher-order types
• Actors
• Scalaz
• Higher-order types
• Parser Combinators
• Actors
• Scalaz
• Higher-order types
• Parser Combinators
• ScalaTest / ScalaCheck
Ik wil meer!
