Kristian Bendiksen kriben

What is the appeal of dynamically-typed languages?

Kris Nuttycombe asks:

I genuinely wish I understood the appeal of unityped languages better. Can someone who really knows both well-typed and unityped explain?

I think the terms well-typed and unityped are a bit of question-begging here (you might as well say good-typed versus bad-typed), so instead I will say statically-typed and dynamically-typed.

I'm going to approach this article using Scala to stand-in for static typing and Python for dynamic typing. I feel like I am credibly proficient both languages: I don't currently write a lot of Python, but I still have affection for the language, and have probably written hundreds of thousands of lines of Python code over the years.

Integer Hash Function

Thomas Wang, Jan 1997

last update Mar 2007

	int read_bool (char *p)
	{
	static const uint64_t true_mask = 0x00000000ffffffff;
	static const uint64_t true_bits = 0x0000000065757274;
	static const uint64_t false_mask = 0x000000ffffffffff;
	static const uint64_t false_bits = 0x00000065736c6166;

	static const uint64_t to_lower = 0x2020202020202020;

	uint64_t next8 = (uint64_t )p \| to_lower;

	# install needed libraries
	sudo yum install texinfo libXpm-devel giflib-devel libtiff-devel libotf-devel

	# compile autoconf
	cd /tmp
	wget ftp://ftp.gnu.org/gnu/autoconf/autoconf-2.68.tar.bz2
	tar xjvf autoconf-2.68.tar.bz2
	cd autoconf-2.68/
	./configure && make && sudo make install

	Latency Comparison Numbers (~2012)
	----------------------------------
	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

Kristian Bendiksen kriben

What is the appeal of dynamically-typed languages?

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Integer Hash Function