Re: [Haskell-cafe] How can i set the seed random number generator ?

2009-12-22 Thread Scott Turner 
On Monday 21 December 2009 20:37:30 zaxis wrote:
 In erlang, first i use the following function to set the seed:
 new_seed() -
 {_,_,X} = erlang:now(),
 {H,M,S} = time(),
 H1 = H * X rem 32767,
 M1 = M * X rem 32767,
 S1 = S * X rem 32767,
 put(random_seed, {H1,M1,S1}).
 
 then use random:uniform/1 to get the random number.
 
 In haskell, i just use the following function to get the random number. It
 seems i donot need to set the seed of random number generator manually?
 
 rollDice ::  Int - IO Int
 rollDice n = randomRIO(1,n)

That's correct.   randomRIO uses the global random number generator which is 
automatically initialized with a different seed each time your program starts 
up.
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Re: [Haskell-cafe] How can i set the seed random number generator ?

2009-12-22 Thread Chaddaï Fouché 
On Tue, Dec 22, 2009 at 1:16 PM, Scott Turner 1hask...@pkturner.org wrote:
 In haskell, i just use the following function to get the random number. It
 seems i donot need to set the seed of random number generator manually?

 rollDice ::  Int - IO Int
 rollDice n = randomRIO(1,n)

 That's correct.   randomRIO uses the global random number generator which is
 automatically initialized with a different seed each time your program starts
 up.

but you can always change it with setStdGen, and you can always use
the non-IO part of System.Random (or even another random library
altogether, particularly recommended if you need performances as
System.Random is more than slow).

-- 
Jedaï
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[Haskell-cafe] How can i set the seed random number generator ?

2009-12-21 Thread zaxis 

In erlang, first i use the following function to set the seed:
new_seed() -
{_,_,X} = erlang:now(),
{H,M,S} = time(),
H1 = H * X rem 32767,
M1 = M * X rem 32767,
S1 = S * X rem 32767,
put(random_seed, {H1,M1,S1}).

then use random:uniform/1 to get the random number.

In haskell, i just use the following function to get the random number. It
seems i donot need to set the seed of random number generator manually?

rollDice ::  Int - IO Int
rollDice n = randomRIO(1,n)

Sincerely!

-
fac n = foldr (*) 1 [1..n]
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