scala – When can you use traits

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala when use trait

When can you use traits?

There is no specific rule when you can use traits, but there is a guideline which you can consider.

a) If the behaviour will not be reused, then make it a concrete class. Anyhow it is not a reusable behaviour.

b) In order to inherit from it in Java code, an abstract class can be used.

c) If efficiency is a priority then lean towards using a class

d) Make it a trait if it might be reused in multiple and unrelated classes. In different parts of the class hierarchy only traits can be mixed into different parts.

e) You can use abstract class, if you want to distribute it in compiled form and expects outside groups to write classes inheriting from it.

scala – trait

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala trait

What is ‘scala trait’ in scala?

‘Traits’ are used to define object types specified by the signature of the supported methods. Scala allows to be partially implemented but traits may not have constructor parameters. A trait consists of method and field definition, by mixing them into classes it can be reused.

scala – function call – recursion tail

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala recursion tail

What is recursion tail in scala?

‘Recursion’ is a function that calls itself. A function that calls itself, for example, a function ‘A’ calls function ‘B’, which calls the function ‘C’. It is a technique used frequently in functional programming.

In order for a tail recursive, the call back to the function must be the last function to be performed.

scala – difference between class object

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala class object

Mention the difference between an object and a class ?

A class is a definition for a description. It defines a type in terms of methods and composition of other types. A class is a blueprint of the object. While, an object is a singleton, an instance of a class which is unique.

scala – variables vals

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala variables vals

What are the Scala variables?

Values and variables are two shapes that come in Scala. A value variable is constant and cannot be changed once assigned. It is immutable, while a regular variable, on the other hand, is mutable, and you can change the value.

The two types of variables are

var myVar : Int=0;

val myVal: Int=1;

scala – better language

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala better language

In what ways Scala is better than other programming language?

a) The arrays uses regular generics, while in other language, generics are bolted on as an afterthought and are completely separate but have overlapping behaviours with arrays.

b) Scala has immutable “val” as a first class language feature. The “val” of scala is similar to Java final variables. Contents may mutate but top reference is immutable.

c) Scala lets ‘if blocks’, ‘for-yield loops’, and ‘code’ in braces to return a value. It is more preferable, and eliminates the need for a separate ternary operator.

d) Singleton has singleton objects rather than C++/Java/ C# classic static. It is a cleaner solution

e) Persistent immutable collections are the default and built into the standard library.

f) It has native tuples and a concise code

g) It has no boiler plate code

scala – advantage

November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala lang advantage

What is the advantage of Scala?

a) Less error prone functional style

b) High maintainability and productivity

c) High scalability

d) High testability

e) Provides features of concurrent programming

scala – map

November 10, 2016November 14, 2016 corerootz - Ravi Kiran Krovvidi Scala scala Map

What is a ‘Scala map’?

Scala map is a collection of key or value pairs. Based on its key any value can be retrieved. Values are not unique but keys are unique in the Map.

scala – set

November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala Set

What is a ‘Scala set’? What are methods through which operation sets are expressed?

Scala set is a collection of pairwise elements of the same type.

Scala set does not contain any duplicate elements.

There are two kinds of sets, mutable and immutable.

scala – wild card pattern

November 10, 2016November 10, 2016 corerootz - Ravi Kiran Krovvidi Scala scala wildcard pattern

The wildcard pattern (_) matches any object whatsoever. You have already seen it used as a default, catch-all alternative, like this:
expr match {

case BinOp(op, left, right) => println(expr +” is a binary operation”)

case _ => }

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Author: corerootz - Ravi Kiran Krovvidi