Some very small steps towards an uuid generation module.

I did some basic research on cross-platform UUID generation and didn't want to lose any information, so this code only represents what I learned (uuidMacTime should work tho).

lib/pure/uuid.nim

@@ -0,0 +1,30 @@
+# This module implements the RFC 4122 specification for generating universally unique identifiers
+# http://en.wikipedia.org/wiki/Universally_unique_identifier
+
+# This module is a work-in-progress
+# If you want to help with the implementation, take a loot at:
+# http://dsource.org/projects/tango/docs/current/tango.util.uuid.Uuid.html
+
+type TUuid* = array[0..15, char]
+
+when defined(windows):
+  # This is actually available only on Windows 2000+
+  type PUuid* {.importc: "UUID __RPC_FAR *", header: "<Rpc.h>".} = ptr TUuid
+  proc uuid1Sys*(uuid: PUuid) {.importc: "UuidCreateSequential", header: "<Rpc.h>".}
+
+else:
+  type PUuid {.importc: "uuid_t", header: "<uuid/uuid.h>".} = ptr TUuid
+  proc uuid1Sys*(uuid: PUuid) {.importc: "uuid_generate_time", header: "<uuid/uuid.h>".}
+
+# v1 UUIDs include the MAC address of the machine generating the ID and a timestamp
+# This scheme has the strongest guaranty of uniqueness, but discloses when the ID was generated
+proc uuidMacTime* : TUuid = uuid1Sys(addr(result))
+
+# v4 UUID are created entirely using a random number generator.
+# Some bits have fixed value in order to indicate the UUID type
+proc uuidRandom*[RandomGenerator](rand: RandomGenerator) : TUuid = nil
+
+# v3 and v5 UUIDs are derived from given namespace and name using a secure hashing algorithm.
+# v3 uses MD5, v5 uses SHA1.
+proc uuidByName*[Hash](namespace: TUuid, name: string, hasher: Hash, v: int) : TUuid = nil
+