Active Directory user GUID

Lars Erik Jordet — Tue, 06 Jul 2010 13:26:36 +0000

I found this page which contains an old oneliner to get a user GUID in PowerShell – but sadly it doesn’t work anymore.

After some tricking around, I found the following to work:

1	(new-object Guid(,(([directoryservices.directorysearcher] "(samaccountname=theuser)").findall())[0].properties["objectguid"][0])).ToString()

deadbeef random number generator in F#

Lars Erik Jordet — Wed, 18 Nov 2009 15:53:24 +0000

I found the Deadbeef Random Number Generator when reading the Reddit thread “What’s the best / most interesting piece of code you’ve ever seen?” – and since I’m trying to learn F#, I figured I could try implementing it, first in an “imperative” way, then in a more functional way.

First the imperative way, a kind of naïve translation of the C code presented:

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let mutable (deadbeef_seed:uint32) = uint32 0;
let mutable (deadbeef_beef:uint32) = uint32 0xdeadbeef;

let deadbeef_srand x =
let oldseed = deadbeef_seed
deadbeef_seed <- x
deadbeef_beef <- uint32 0xdeadbeef
oldseed

let deadbeef_rand () =
deadbeef_seed <- (deadbeef_seed <<< 7) ^^^ ((deadbeef_seed >>> 25) + deadbeef_beef);
deadbeef_beef <- (deadbeef_beef <<< 7) ^^^ ((deadbeef_beef >>> 25) + (uint32 0xdeadbeef));
deadbeef_seed;

This is not very functional, with mutables and all that, so I tried again, with an implementation requiring no mutable variables:

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let deadbeef_rand_seq seed = seq {
let rec db_rand seed beef = seq {
let newseed = (seed <<< 7) ^^^ ((seed >>> 25) + beef);
let newbeef = (beef <<< 7) ^^^ ((beef >>> 25) + (uint32 0xdeadbeef));
yield newseed
yield! db_rand newseed newbeef
}
yield! db_rand seed (uint32 0xdeadbeef)
}

…much better (at least in my opinion); implemented as a sequence of random numbers, deadbeef_rand_seq(seed).Take(10) would give you 10 random uint32s.
I’ll bet there are about 1000 other ways to make this more F#-like/more functional, so I’d love to hear about them!

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Active Directory user GUID

deadbeef random number generator in F#