README.md

@@ -1,27 +0,0 @@
-# Math Types
-
-A typescript library that aims to provide performant arithmetic types.
-
-# Limitations
-
-Currently math-types does not support negative numbers, decimals, or bigints.
-
-# Types
-
-### Add<A extends number, B extends number>
-
-Resolves to the sum of A and B
-The corresponding function `add` uses this type
-
-### Max<A extends number, B extends number>
-
-Resolves to the larger of A and B
-The corresponding function `max` uses this type
-
-# Current Roadmap
-
-- Subtraction
-- Support negative numbers
-- Support decimal numbers
-- Multiplication
-- Division

index.ts

@@ -1,3 +0,0 @@
-export * from './src/Addition'
-export * from './src/Max'
-export * from './src/Digits'

package.json

@@ -1,15 +1,14 @@
 {
-  "name": "math-types",
-  "version": "0.0.2",
+  "name": "numeric-types",
+  "version": "1.0.0",
   "description": "",
   "main": "index.js",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1"
   },
   "author": "Jeff Lieb",
-  "license": "NON-AI ISC",
+  "license": "ISC",
   "dependencies": {
     "typescript": "^5.3.3"
-  },
-  "keywords": ["typescript", "math", "add", "max"]
+  }
 }

src/Addition.ts

@@ -1,4 +1,4 @@
-import { DigitsToNumber, SplitDigits, Digit, TupleForDigit } from "./Digits";
+import { DigitsToNumber, SplitDigits, Digit, TupleForDigit } from ".";
 
 
 export type Add<A extends number, B extends number> = DigitsToNumber<AddDigitArrays<SplitDigits<A>, SplitDigits<B>>> & number

src/Max.ts

@@ -1,5 +1,5 @@
 
-import { Digit, DigitsToNumber, SplitDigits, TupleForDigit } from "./Digits"
+import { Digit, DigitsToNumber, SplitDigits, TupleForDigit } from "."
 
 export type Max<A extends number, B extends number> = DigitsToNumber<MaxDigitArray<SplitDigits<A>, SplitDigits<B>>> & number
 

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
+
+

src/index.ts

@@ -1,4 +1,6 @@
-export type Digit = 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
+type NonZeroDigit = 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9
+export type Digit = 0 | NonZeroDigit
+type Tuple0To9 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 
 export type TupleForDigit<Value extends Digit> = 
     Value extends 0 ? []
@@ -25,6 +27,8 @@ type TakeDigitFromString<DigitString extends String> =
             ? [Head, ...TakeDigitFromString<Tail>]
             : never
 
+type Zeros<Length extends number> = [] & {length: Length} extends [...infer Tuple] ? {[Property in keyof Tuple]: 0} & Array<0> & {length: Length} : never
+
 type StringToNumber<NumericString extends string> = NumericString extends `${infer Number extends number}` ? Number : never
 
 type Stringable = string | number | bigint | boolean | null | undefined