Does Your Programming Language Ever Surprise You in a Good Way? | MediumSitemapOpen in appSign up<br>Sign in

Medium Logo

Get app<br>Write

Search

Sign up<br>Sign in

Does Your Programming Language Ever Surprise You in a Good Way?

Donald Raab

3 min read·<br>1 hour ago

Listen

Share

What does two divided by three return in your programming language?

Press enter or click to view image in full size

Photo by Claudio Schwarz on Unsplash

When I learned Smalltalk in the 1990s, I experienced a surprise that no other programming language I had learned up to that point prepared me for.<br>What is behind door 2 / 3?

The answer to this question varies by programming language. Smalltalk changes the script. The answer to this question in Smalltalk is a Fraction.

Press enter or click to view image in full size

In Smalltalk, the result of 2 / 3 is a Fraction

Wut the?

The real surprise as it turns out is not that Smalltalk has support for fractions. That was the initial surprise. The real surprise is how / works. The / in Smalltalk is a binary message sent to the SmallInteger 2 with the parameter 3, which is also a SmallInteger. Smalltalk is dynamically typed, so the return type is not required to be an SmallInteger.<br>This is the implementation of / as defined on SmallInteger. You can see the other types that define / as well here.

Press enter or click to view image in full size

Finding the implementors of /, and browsing the definition of / for SmallInteger.

Now an interesting surprise here is the definition of / for Collection. Let’s divide two arrays and see what we get back.

Press enter or click to view image in full size

Dividing two arrays results in the results stored in a third array

Now let’s divide a single array with a SmallInteger.

Press enter or click to view image in full size

Dividing an array with a SmallInteger

Now let’s flip it and divide the SmallInteger by the array.

Press enter or click to view image in full size

Dividing a SmallInteger by an array

Now let’s make my final point, about being surprised by your programming language.

Press enter or click to view image in full size

Combining two arrays into an array of Points

Writing this blog was a bit surprising for me. I wasn’t sure where I was going to go with this. I knew I would start with Fractions, because those are surprising enough in a programming language. But I didn’t expect to be doing math with collections. We explored just a bit about binary messages. If it isn’t obvious, you can define binary messages on your own objects. You might refer to this as operator overloading, but that’s a kind of dismissive way to think about what Smalltalk is doing here.<br>The whole of Smalltalk is defined as sending messages to objects. Here we send the message / to some object. Either the object responds with a an appropriate result to the message, or responds that it does not understand the message. In this regard, a / is no different than any other message, with the exception that binary messages like / can only have one parameter.<br>I hope this exploration was a nice surprise for you. It was for me.<br>Thanks for reading!<br>Note: I used the open source Pharo Smalltalk 13.0 for these code examples.<br>I am the creator of and committer for the Eclipse Collections OSS project, which is managed at the Eclipse Foundation. Eclipse Collections is open for contributions. I am the author of the book, Eclipse Collections Categorically: Level up your programming game.

Smalltalk

Programming

Open Source

Object Oriented

Written by Donald Raab

2.5K followers<br>·340 following

Java Champion. Creator of the Eclipse Collections OSS Java library (https://github.com/eclipse-collections). Inspired by Smalltalk. Opinions are my own.

Help

Status

About

Careers

Press

Blog

Store

Privacy

Rules

Terms

Text to speech