Max of rotated numbers kata (shared array support)

[edA-qa mort-ora-y]

This is a solution to the rotate-for-a-max kata.

I needed to add support for `shared array` since somehow I overlooked that before.  It's not an ideal implementation yet, as it does a double allocation rather than just store the array bits directly in the shared object. There looks to be a bit of cleanup required of the basic memory management stuff -- too many functions and oddities involved.

import std
import math

defn rot_max = ( n : integer ) -> {
	n < 0 then fail string_tag( "negative-not-supported" )
	n == 0 then return n
	
	var mx = n
	
	//convert into array of digits
	var maxDigits = num_decimal_digits(n)
	var digits = type｢shared array｢integer｣｣(maxDigits)
	var digitCount = 0
	loop n > 0 ? {
		digits#digitCount = mod(n, 10)
		n /= 10
		digitCount+=1
	}
	
	for i in std.range(digitCount, 0) {
		rotate( digits, 0, i )
		var s = add(digits, digitCount)
		mx = max( mx, s )
	}
	
	return mx
}

defn add = ( digits : shared array｢integer｣, digitCount : integer ) -> {
	var r : integer = 0
	for i in std.incl_range(digitCount-1,0) {
		r *= 10
		r += digits#i
	}
	return r
}

defn rotate = ( digits : shared array｢integer｣, start : integer, end : integer ) -> {
	end <= start then return
	
	var t = digits#(end-1)
	for i in std.range(end-1, start) {
		digits#i = digits#(i-1)
	}
	digits#start = t
}

defn max = ( a, b ) -> {
	return a > b ? a | b
}

defn num_decimal_digits = ( x : integer ) -> ( : integer ) {
	var l = math.log10(lossy(x))
	return lossy(l+1)
}

var main = -> {
	dotest(38458215, 85821534);
	dotest(195881031, 988103115);
	dotest(896219342, 962193428);
	dotest(69418307, 94183076);
	dotest(257117280, 571172802);
	dotest(240522578, 452782025);
	dotest(561656824, 666824515);
	dotest(672963486, 796348662);
	dotest(48192242, 89242412);
	dotest(25053359, 55392035);
	dotest(785727925, 877925752);
	dotest(275076894, 750768942);
	dotest(507992495, 507992495);
	dotest(461358517, 638517415);
	dotest(563692037, 669203753);
	dotest(159043701, 590437011);
	dotest(896304934, 963049348);
	dotest(273293210, 732932102);
	dotest(451496516, 549651641);
	dotest(1, 1);
	
	dotest(16130873362142, 63873362142110);
	dotest(84005278654009, 84005278654009);
	dotest(51564279810300, 51564279810300);
	dotest(12364484492416, 26484492416134);
	dotest(63026816035764, 63026816035764);
	dotest(77910393341241, 79103933412417);
	dotest(88700243816673, 88700243816673);
	dotest(65879065959482, 65879065959482);
	dotest(88361793184682, 88361793184682);
	dotest(91556298303742, 91556298303742);	
}

defn dotest = ( n : integer, mx : integer ) -> {
	var r = rot_max( n )
	r != mx then {
		std.print([ n, ": Actual(", r, ") Expect(", mx, ")\n"])
	}
}