Password-based authentication has a number of drawbacks, so many services (such as github) use SSH keys to authenticate. However distributing the keys over several nodes (be virtual machines or single-board computers such as Raspberry Pi) doesn’t scale over the number of nodes and users.

Luckily, OpenSSH implementation of SSH supports a certificate-based mechanism. This mechanism may help reducing the complexity of users trusting SSH hosts and hosts trusting SSH users.

Recently the committee that is preparing the next standard of C++, known as C++20, approved the inclusion of modules. Modules are good™ but they pose some interesting challenges to implementors and users. In this post I will ruminate a bit about what challenges have impacted Fortran.

In the last installment of this series we started to look at the AST and the symbol table by examining the compiler dumps of these two data structures. In this chapter we are going to explore a bit more the AST for the control flow statements.

Use case

I've been willing to give the serverless framework a try for a while, and recently I came up with a small side project that was a potential good fit for it.

I am a Monzo user, and I use their card to pay for things like my weekday lunches around the office or my travel expenses like Oyster Card top ups. I also happen to be a user of Toshl, which helps me with my personal finances and budgets.

Typically, whenever my Oyster card gets topped up or I pay for a lunch in a restaurant, I then input that expense into Toshl. But turns out both Monzo and Toshl are developer friendly, so I thought I could easily automate that process by having a system that would get certain Monzo expenses directly into Toshl for me, saving me a few seconds per day.

A serverless approach was ideal for this, especially since AWS offers a free tier for its services, meaning this would also not cost me a penny.

In previous chapters we saw how the input source was lexed, parsed and semantically analysed and we looked at how the symbols and data types are represented. But we haven't looked at what happens once the semantic analysis finishes. In this installment we're going to talk about the AST.