Introduce bitwise operators (in a module)

[masak]

Operators that treat integers as bit sequences could definitely have a place in today's 007, if it weren't for the fact that they aren't so much on the hot path for the inner workings of a compiler tool chain.

My thinking lately though is that they have a place both (a) as opcodes in an eventual runtime/VM, and (b) as user-exposed operators through a language-extending module or two.

Why? Basically three reasons:

• While they aren't vital for the inner workings of a compiler tool chain, they do tend to be vital on the periphery. Reading and writing from files means dealing with bytes and encoding/decoding. Something like a checksum algorithm will want to take a byte view on things.

• Ever since I wrote examples/nim-addition.007, I've felt that it's quite silly that we don't have anything neat and low-level to use for bitwise exclusive or. Even if the base language doesn't expose an operator for it, there should be a bytecode opcode that we can just dig down to and use. (It's a rare case of being stuck at too high an abstraction level!)

• There are a fair amount of optimizations that generate opcodes doing bitwise arithmetic.

There are two possible syntaxes to choose from for all the bitwise operators:

name	C-family style	Perl 6 style
bitwise negation	~	prefix:<+^>
bitwise and	&	infix:<+&>
bitwise or	|	infix:<+|>
bitwise xor	^	infix:<+^>
left shift	<<	infix:«+<»
right shift	>>	infix:«+>»

In order to make this issue actionable, I'd consider it closed when both of those syntaxes are available through language-extending modules. The runtime/VM opcodes can wait until we have a dedicated runtime.