This blog post has been published on the Preferred Networks Tech Blog.
Pattern matching on algebraic data types is a powerful technique to process a given input and many programming languages have adopted it in one way or another. In this blog post I will first briefly explain the concept of sum types and give examples of pattern matching on these types in Rust and Scala. Then I will show how to define sum types in recent Python versions, and I will explain how the mypy type checker can (to a limited degree) be used to add exhaustiveness checks to Python code working with these types.
This blog post has been published on the Preferred Networks Tech Blog.
Most computer applications can be configured to behave a certain way, be it via command line flags, environment variables, or configuration files. For you as a software developer, dealing with configuration comes with challenges such as parsing untrusted input, validating it, and accessing it on all layers of your program. Using Python as an example, I want to share some best practices to help you handle configuration safely and effectively.
Timestamps in Apache access log files have, by default, the format 27/Oct/2013:06:33:40 +0100. This can not be parsed in Python using the strptime() function from the time/datetime modules because there is no %z placeholder in strptime() to match the timezone (only %Z). Also, using the parse() function from dateutil.parser ...