Andre Almar andrealmar

Pure vs impure and why should I care?

Some of the most important advancements in programming came from adding restrictions to the way we program. Famous article by Edsger Dijkstra Go To Statement Considered Harmful shows how introducing one statement into programming language breaks many nice properties of that language. goto gives us freedom and solves couple of simple problems like breaking from nested loops easily, but it can make programs very hard to understand. This happens, because we cannot look at two pieces of code in spearation. The execution can jump to some other place in code or even worse: it can jump from other piece of code to here and We need to keep that in mind.

Some books I've been studying to improve my skills as a SRE/System Engineer.

Transforming Code into Beautiful, Idiomatic Python

Notes from Raymond Hettinger's talk at pycon US 2013 video, slides.

The code examples and direct quotes are all from Raymond's talk. I've reproduced them here for my own edification and the hopes that others will find them as handy as I have!

Looping over a range of numbers

for i in [0, 1, 2, 3, 4, 5]:

	Latency Comparison Numbers
	--------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD