Combinatorics in a functional way
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Date:  20070221 (13:46) 
From:  Fernando Alegre <fernando@c...> 
Subject:  Re: [Camllist] Combinatorics in a functional way 
Hi, This is what I would do: let get i (i0,i1,i2,i3,i4,i5,i6,i7) = match i with  0 > i0  1 > i1  2 > i2  3 > i3  4 > i4  5 > i5  6 > i6  7 > i7  _ > invalid_arg "get" let set i (i0,i1,i2,i3,i4,i5,i6,i7) x = match i with  0 > (x,i1,i2,i3,i4,i5,i6,i7)  1 > (i0,x,i2,i3,i4,i5,i6,i7)  2 > (i0,i1,x,i3,i4,i5,i6,i7)  3 > (i0,i1,i2,x,i4,i5,i6,i7)  4 > (i0,i1,i2,i3,x,i5,i6,i7)  5 > (i0,i1,i2,i3,i4,x,i6,i7)  6 > (i0,i1,i2,i3,i4,i5,x,i7)  7 > (i0,i1,i2,i3,i4,i5,i6,x)  _ > invalid_arg "set" let next bounds index = let rec loop i index = if i = 8 then index else let x = get i index in if x < get i bounds then set i index (x+1) else loop (i+1) (set i index 0) in loop 0 index let fold f acc bounds = let rec next i index = if i = 7 then index else if index < get i bounds then set i (index+1) else next (i+1) (set i index 0) and loop a index = if i = 8 then acc else loop (f a index) (next bounds index) in loop 0 (0,0,0,0,0,0,0) let find_combi ((p0,p1,p2,p3,p4,p5,p6,p7) as bounds) = fold (fun l x > x :: l) [] bounds Fernando On Wed, Feb 21, 2007 at 08:36:03PM +1100, Erik de Castro Lopo wrote: > Hi all, > > I'm currently working on something where I need to to generate a > set of permutations that fit a set of rules. Currently I am doing > something like: