WIP subtraction/comparison stuff

src/Comparison.ts

@@ -0,0 +1,39 @@
+
+import { Digit, DigitsToNumber, TupleForDigit } from "."
+
+type GreaterThan<A extends number, B extends number> = DigitsToNumber<[5]>
+
+
+type Max<A extends number, B extends number> = never
+
+type MaxDigitArray<A extends Digit[], B extends Digit[]> = 
+    A extends B
+        ? A | B
+        : MaxByLength<A, B> extends A | B 
+            ? MaxDigit<Head<Digit, A>, Head<Digit, B>> extends Head<Digit, A> | Head<Digit, B>
+                ? [Head<Digit, A>, ...MaxDigitArray<Tail<Digit, A>, Tail<Digit, B>>]
+                : MaxDigit<Head<Digit, A>, Head<Digit, B>> extends Head<Digit, A> 
+                    ? A
+                    : B
+            : MaxByLength<A, B>
+
+type MaxDigit<A extends Digit, B extends Digit> = 
+    MaxByLength<TupleForDigit<A>, TupleForDigit<B>> extends TupleForDigit<A> ? A
+     : MaxByLength<TupleForDigit<A>, TupleForDigit<B>> extends TupleForDigit<A> | TupleForDigit<B> ? A | B
+     : B
+
+type MaxByLength<A extends any[], B extends any[]> =
+    A['length'] extends B['length'] ? A | B
+    : ToZeros<A> extends [...infer Other, ...ToZeros<B>] ? A
+    : B
+
+type ToZeros<Tuple extends any[]> = { [Property in keyof Tuple]: 0}
+
+type HeadTail<Type, Tuple extends Type[]> = Tuple extends [infer Head extends Type, ...infer Tail extends Type[]] ? [Head, Tail] : never
+
+type Head<Type, Tuple extends Type[]> = Tuple extends [infer Head extends Type, ...Type[]] ? Head : never 
+type Tail<Type, Tuple extends Type[]> = Tuple extends [Type, ...infer Tail extends Type[]] ? Tail : never
+
+let q: MaxDigitArray<[2, 0, 2], [2, 1]>
+
+let x: ToZeros<[2, 0]>

src/Subraction.ts

@@ -0,0 +1,15 @@
+import { Digit, DigitsToNumber, SplitDigits, TupleForDigit } from ".";
+
+export type Add<A extends number, B extends number> = DigitsToNumber<SubtractDigitArrays<SplitDigits<A>, SplitDigits<B>>> & number
+
+type SubtractDigitArrays<A extends Digit[], B extends Digit[], Carry extends boolean = false> = 
+    [A, B] extends [[...infer HeadA extends Digit[], infer TailA extends Digit], [...infer HeadB extends Digit[], infer TailB extends Digit]] ? AddTails<HeadA, TailA, HeadB, TailB, Carry> : [A, B] extends [[...infer HeadA extends Digit[], infer TailA extends Digit], []] ? AddTails<HeadA, TailA, [], 0, Carry> : [A, B] extends [[], [...infer HeadB extends Digit[], infer TailB extends Digit]] ? AddTails<[], 0, HeadB, TailB, Carry> : [A, B] extends [[], []] ? Carry extends true ? [1] : [] : []
+
+type SubtractTails<HeadA extends Digit[], TailA extends Digit, HeadB extends Digit[], TailB extends Digit, Carry extends boolean> = 
+    SplitDigits<SubtractDigits<TailA, TailB, Carry>> extends [1, infer Result extends Digit] ? [...AddDigitArrays<HeadA, HeadB, true>, Result] : [...AddDigitArrays<HeadA, HeadB>, SplitDigits<AddDigits<TailA, TailB, Carry>>[0]]
+
+type SubtractDigits<A extends Digit, B extends Digit, Carry extends boolean = false> =
+    
+    [...TupleForDigit<A>, ...TupleForDigit<B>, ...(Carry extends false ? [] : [0])]['length'] & number
+
+