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open Array
let foldi_left f st a =
let len = length a in
let rec loop st i =
if i = len then st
else
loop (f st i (unsafe_get a i)) (i+1)
in
loop st 0
let foldi_right f a st =
let len = length a in
let rec loop st i =
if i = -1 then st
else
loop (f i (unsafe_get a i) st) (i+1)
in
loop st (len-1)
let shuffle ?(random=Random.int) a =
let len = length a - 1 in
for i = 0 to len - 1 do
let d = len - i in
let j = random d + i in
let x = unsafe_get a i in
let y = unsafe_get a j in
unsafe_set a i y;
unsafe_set a j x;
done