I'm writing an application that needs fast, high-quality random number generation, so I've been implementing a Mersenne Twister random number generator. I'm finding that bit-twiddling in Clojure can be a "bit" awkward. Here are some specifics:
1. bit-and, bit-or, and bit-xor only take two arguments. These are all associative operations, and as such should take an arbitrary number of arguments for the same reason that + and * take arbitrary number of arguments: so you can write, e.g., (op a1 a2 a3 a4) instead of (op (op (op a1 a2) a3) a4) 2. There is no direct support for word-level, unsigned shifts. That is, I want to treat an int as the equivalent 32-bit unsigned value when I do the shift, shifting in 0 bits and dropping the bits that shift past the word boundaries. It took a while to figure out how to do this correctly; the biggest problem was avoiding the propagation of the sign bit on a right shift. After experimenting around for a while I figured out that these will work: * Left-shift x by n bits: (int (bit-shift-left x n)). * Right-shift x by n bits: (int (bit-shift-right (bit-and intmask x) n)) where intmask = 2^32 - 1. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
