Wednesday, April 3, 2013

Scala: Parameter-less functions

Scala has a few tripping points for newbies and one of them is parameter-less functions which look just like variable names or field names. I came across a very interesting example when researching the difference between def and val in Scala:

Scala has three ways to define a variable, method name or object:

def defines a method
val defines a fixed value (which cannot be modified - these are like Java final variables)
var defines a variable (which can be modified later). These are discouraged in Scala since they are mutable and are indicative that the program is using an imperative style of programming.

Consider the following example which may fool you ( from this question on stackoverflow):

class Person(val name:String,var age:Int )

def person =new Person("Kumar",12)

person.age=20

println(person.age)

These lines of code give output as 12. ALWAYS. The reason is that " def person" creates a function definition instead of an object. Thus each time you write person in the code, it refers to a brand new Person object created by the person method. This happens in the assignment as well as the println code!

Another example from the "Programming in Scala, 2nd Edition" - If a function literal

consists of one statement that takes a single argument, you need not explicitly

name and specify the argument. Thus, the following code works and println looks like the name of variable in this case:

args.foreach(println)

About Tukeys

Tukeys provides consulting and software services to companies in healthcare and communications that are dealing with technical or scaling challenges. Please reach out to me on LinkedIn.

An interesting quote from John Tukey, who was an American mathematician (1915-2000) -

An approximate answer to the right problem is worth a good deal more than an exact answer to an approximate problem.

Today maths and statistics form the basis of how software is developed and used around us.

About Me

I have over 20 years of experience in healthcare, communications and AI.

I have a passion for defining innovative applications, creating product/technology strategy and solving challenging problems. My product mindset is helpful to any company to find patterns, reduce costs, and gain efficiencies.

I was the VP of Engineering at Vibrent Health, where I led the web, mobile, API and data products that supported one of the largest NIH programs - All of Us Research Program. Our system enrolled almost a million users and collected data from EHRs, surveys and wearables. Before that, I worked at hCentive, a pioneer in health exchanges.

As the CTO of 3CLogic, I helped create the first PC and web-only contact center solution that implemented PBX and CRM functionality as an affordable SaaS solution. As the Chief Architect of NexTone, I was instrumental in the development of SIP and SIP based products. SIP and associated protocols form the basis of modern WebRTC APIs.

If you are a growth company or invest in growing companies that are facing technical or scaling challenges, I can be a tremendous help. Contact me on LinkedIn.

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