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{ Category Archives } code-level

Working Effectively with Legacy Code

I gave a talk to my team at ARM today on Working Effectively with Legacy Code by Michael Feathers. Here are some notes I made in preparation, which are somewhat related to the talk I gave. This may be the most important book a software developer can read. Why? Because if you don’t, then you’re […]

Build systems are a huge annoyance

Take Smalltalk. Do I have an object in my image? Yes? Well I can use it. Does it need to do some compilation or something? I have no idea, it just runs my Smalltalk. Take Python. Do I have the python code? Yes? Well I can use it. Does it need to do some compilation […]

The package management paradox

There was no need to build a package management system since CPAN, and yet npm is the best. Wait, what? Every time a new programming language or framework is released, people seem to decide that: It needs its own package manager. Simple algorithms need to be rewritten from scratch in “pure” $language/framework and distributed as […]

Apple’s Best Programming Language

My talk at App Builders 2016 was on Apple’s best programming language. Spoiler alert: it’s Dylan. Or is it? I chose a few properties one might wish to find in programming languages, then demonstrated how these were all present in the Dylan language. I also took a dig at certain other languages, which do things […]

Did that work? Maybe.

A limitation with yesterday’s error-preserving approach is that it leaves you on your own to recover from problems. Assuming your error definitions are sufficiently granular, this should be straightforward but tedious. Find out what went wrong, recover from it, then replay everything that happened afterwards. Recovering from failures automatically is difficult in general, after all, […]

Getting better at doing it wrong

For around a month at the end of last year, I kept a long text note called “doing doing it wrong right”. I was trying to understand error handling in programming, look at some common designs and work out a plan for cleaning up some error-handling code I was working with myself (mercifully someone else, […]

An acceptable tool

An acceptable tool It’s easy to forget that adequacy is, well, adequate. It’s easy to go all-in on making some code structure perfect, when good enough would be good enough.

Hiding behind messages

A problem I think about every so often is how to combine the software design practice of hiding implementations behind interfaces with the engineering practice of parallel execution. What are the trade-offs between making parallelism explicit and information hiding? Where are some lines that can be drawn? Why do we need abstractions for this stuff, […]

Fun and games (with rewritten rules) in Objective-C

An object-oriented programming environment is not a set of rules. Programs do not need to be constructed according to the rules supplied by the environment. An object-oriented environment includes tools for constructing new rules, and programs can use these to good effect. Let’s build multiple method inheritance for Objective-C, to see a new set of […]


Sadly it’s not called Schoenfinkeling, but that’s the name of the person who noticed that there’s no reason to ever have a function with more than one argument. What you think is a function with two arguments is actually a function with one argument that returns a function with one argument, this second function closing […]