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Knuth shuffle: Difference between revisions
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Line 2,480:
<lang Scheme>
{def shuffle
{def shuffle.in
{lambda {:a}
{S.map {{lambda {:a :i}
{A.swap :i
{floor {* {random} {+ :i 1}}} // j = random integer from 0 to i+1
:a}} :a}
{S.serie {- {A.length :a} 1} 0 -1}}}} // from length-1 to 0
{lambda {:a}
{let { {:b {A.duplicate :a}} } // optionnaly prevents modifying the original array
{S.replace \s by in {shuffle.in :b} // trim extra spaces
:b}}}} // return the new array
-> shuffle
{def A.swap // should probably be promoted as a primitive
{lambda {:i :j :a}
{let { {:i :i}
{:gja {A.get :j :a}}
{:b {A.set! :j {A.get :i :a} :a}}
} {let { {_ {A.set! :i :gja :b} }}}}}} // side effect without any return value
-> A.swap
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