Scala

I finished "Functional Programming Principles in Scala" and for the first time in a long time I am excited about a new programming language.

I did not pick up any compiled typed language for a while. I landed my first job doing JavaScript and it felt like a breath of fresh air after studying C++ at the university.

JavaScript community accepted static analysis through linters (JSLint → JSHint → ESLint), later came type checking with Flow and TypeScript. Flow codebase introduced me to the OCaml language. I was fascinated to learn about the powerful type system and pattern matching. And though the language seems to have a great community of very smart people, lack of toolchain and libraries held me back from learning it deeper.

Scala continues the ideas of OCaml: you can successfully combine object oriented and functional features in a language, mutable and immutable collections.

Here is a short summary about the language and the course.

What I liked about Scala #

• No statements, only expressions
• Operators are method calls
• Inferred types
• Powerful pattern matching
• Structural equality
• Rich built-in collections library
• Maps and sequences are functions (key => value or index => value), brilliant!

What I learned from the course #

Programming language ideas #

• Implicit Parameters
• Partial functions (not to be confused with partial application!)
• Call-by-name as a syntax (f: => T)
• Covariance and contravariance

Computer science ideas #

• Huffman encoding
• how to think about fold left and fold right as a trees:

What surprised me #

• Coming from Flow, I expected union and intersection types, but they are scheduled only for Dotty
• In Scala community (at least in the FP part of it) it seems that the notions of Monoid and Semigroup are common knowledge

Links #

• "Scala exercises" to learn basic language and features
• "Scala with style" talk by Martin Odersky where he explains design decisions he made about the language