Idiomatic Learning

When learning a new language I find it helpful to study a languages idioms. Idioms exist in a language for a specific reason. Sometimes that reason is to further the principles of the language, other times it’s to mask, or otherwise deal with some underlying design decision of the language. Currently, I am studying Haskell, and currently I am struggle to clarify the idioms of the language. The syntax is still very new and awkward, currently with a total authoring in Haskell of 713 lines.

Python has some interesting idioms, but the one that really helped me when learning was “..tuples should have trailing commas…” At that time, the only other language I knew was C, and PIC Assembly. I was very much a hardware engineer, and Python, for me, was a step out of that hardware-centric mindset. So with such a staunch, inflexible background as this, such an idiom felt, dirty and wrong? My first reaction to this was, “What? Really? Why, are python programmers too lazy?” At first I refused to do this, claiming that my source code was more elegant, and clean. However some time later I learned the second part of this idiom, “…tuples should have trailing commas, BECAUSE syntactically the comma creates the tuple, not the parenthesizes.” Whoa! What an epiphany. From this simple clause, I can now create a tuple with 1 element! The because clause of an idiom, really opens doors in your mind. It really clarifies some subtle point, or characteristic of the language.

C++ on the other hand has a number of idioms that have become quite ingrained that it’s hard to separate, “yeah that’s just C++ syntax”, from, “That’s just how I do it,” to, “Oh yeah, I guess template class … isn’t very intuitive is it.” C++ is a complex multi-paradigm language with one sweeping design decision: You pay for what you use. For instance, take class methods. In C++ class methods are not polymorphic by default. I remember as a fledgling C++ programmer asking my computer science friend, Brian, “…classes are useless without polymorphism. That’s just stupid.” He tried to explain it to me, but I was probably to frustrated to understand. What I didn’t know was the because, and I continued my ignorant use of virtual until I read The Design and Evolution of C++  that I learned the reason. Polymorphism requires a level of indirection to implement. Doing so affects performance. C++ doesn’t push this on you unless you want it, just non-polymorphic by default, virtual if you want. Beautiful. Now as an embedded system designer I love this aspect of C++. I am free to use the features I need without paying for the ones I don’t.

So now as I approach Haskell, I read blogs, and statements with a temporary suspension of judgement until I learn the because.

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