{def BS
 {def BS.r {lambda {:a :v :i0 :i1}
  {let { {:a :a} {:v :v} {:i0 :i0} {:i1 :i1}
         {:m {floor {* {+ :i0 :i1} 0.5}}} }
  {if {<  :i1 :i0}
   then :v is not found
   else {if {> {array.item :a :m} :v}
   then {BS.r :a :v :i0 {- :m 1} }
   else {if {<  {array.item :a :m} :v}
   then {BS.r :a :v {+ :m 1} :i1 }
   else :v is at array[:m] }}}}} }
 {lambda {:a :v}
  {BS.r :a :v 0 {- {array.length :a} 1}} }}
-> BS

{def A {array 12 14 16 18 20 22 25 27 30}}
-> A = [12,14,16,18,20,22,25,27,30]

{BS {A} -1}  -> -1 is not found
{BS {A} 24}  -> 24 is not found
{BS {A} 25}  -> 25 is at array[6]
{BS {A} 123} -> 123 is not found

{def B {array {serie 1 100000 2}}}
-> B = [1,3,5,... 99997,99999]

{BS {B} 100}   -> 100 is not found
{BS {B} 12345} -> 12345 is at array[6172]