Notes on computers and other things

Scala

February 12, 2017

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
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