fix: type issues found from tests

src/base/exponents.ts

@@ -11,9 +11,9 @@ export type NegativeExponent<T extends Exponent> = T extends -6
   : T extends -2
   ? 2
   : T extends -1
-  ? 0
-  : T extends 0
   ? 1
+  : T extends 0
+  ? 0
   : T extends 1
   ? -1
   : T extends 2

src/base/index.ts

@@ -7,4 +7,5 @@ export type {
   MultiplyExponents,
   DivideExponents,
 } from "./exponents";
+export { MultiplyUnitExponents, DivideUnitExponents } from "./unit-exponents";
 export type { Multiply, Divide, Inverse } from "./units";

src/base/unit-exponents.ts

@@ -0,0 +1,55 @@
+import { type Unit, type UnitValue, type UnknownUnit } from "./core";
+import {
+  type DivideExponents,
+  type Exponent,
+  type MultiplyExponents,
+} from "./exponents";
+import {
+  type FlatternAlias,
+  type GetUnitConfig,
+  type GetUnitValues,
+} from "./utils";
+
+export type MultiplyUnitExponents<
+  A extends number,
+  B extends 2,
+> = A extends UnknownUnit
+  ? MultiplyUnitExponentsCore<A, B> extends Record<string, UnitValue>
+    ? Unit<FlatternAlias<MultiplyUnitExponentsCore<A, B>>>
+    : never
+  : number;
+
+type MultiplyUnitExponentsCore<A extends UnknownUnit, B extends 2> = {
+  [U in keyof GetUnitConfig<A>]: {
+    [E in keyof GetUnitConfig<A>[U]]: MultiplyExponents<
+      E extends keyof GetUnitValues<GetUnitConfig<A>, U>
+        ? GetUnitValues<GetUnitConfig<A>, U>[E] extends Exponent
+          ? GetUnitValues<GetUnitConfig<A>, U>[E]
+          : 0
+        : 0,
+      B
+    >;
+  };
+};
+
+export type DivideUnitExponents<
+  A extends number,
+  B extends 2,
+> = A extends UnknownUnit
+  ? DivideUnitExponentsCore<A, B> extends Record<string, UnitValue>
+    ? Unit<FlatternAlias<DivideUnitExponentsCore<A, B>>>
+    : never
+  : number;
+
+type DivideUnitExponentsCore<A extends UnknownUnit, B extends 2> = {
+  [U in keyof GetUnitConfig<A>]: {
+    [E in keyof GetUnitConfig<A>[U]]: DivideExponents<
+      E extends keyof GetUnitValues<GetUnitConfig<A>, U>
+        ? GetUnitValues<GetUnitConfig<A>, U>[E] extends Exponent
+          ? GetUnitValues<GetUnitConfig<A>, U>[E]
+          : 0
+        : 0,
+      B
+    >;
+  };
+};

src/functions-ho/index.ts

@@ -1,4 +1,5 @@
 import {
+  type DivideUnitExponents,
   type Divide,
   type Multiply,
   type Inverse,
@@ -64,12 +65,14 @@ export function modSafe<T extends number>(
   return (b) => (((b % a) + a) % a) as OperationIO<T>;
 }
 
-type PowFunction<E extends number, B extends number> = E extends -1
+type PowFunction<E extends number, B extends number> = E extends UnknownUnit
+  ? never
+  : E extends -1
   ? (b: OperationIO<B>) => OperationIO<Inverse<B>>
   : E extends 0
-  ? (b: OperationIO<B>) => Decimal | 1
+  ? (b: OperationIO<B>) => OperationIO<B> extends UnknownUnit ? Decimal : 1
   : E extends 0.5
-  ? (b: OperationIO<B>) => OperationIO<Divide<B, 2>>
+  ? (b: OperationIO<B>) => OperationIO<DivideUnitExponents<B, 2>>
   : E extends 1
   ? (b: OperationIO<B>) => OperationIO<B>
   : E extends 2
@@ -83,10 +86,9 @@ type PowFunction<E extends number, B extends number> = E extends -1
 /**
  * Put a number to the power of the given value.
  */
-export function pow<E extends number, B extends number>(
-  exponent: E extends UnknownUnit ? never : E,
-): PowFunction<E, B> {
-  return ((base: OperationIO<B>) => base ** exponent) as PowFunction<E, B>;
+export function pow<E extends number>(exponent: E) {
+  return <B extends number>(base: Parameters<PowFunction<E, B>>[0]) =>
+    (base ** exponent) as ReturnType<PowFunction<E, B>>;
 }
 
 /**

src/functions/index.ts

@@ -1,4 +1,5 @@
 import {
+  type DivideUnitExponents,
   type Divide,
   type Multiply,
   type Inverse,
@@ -98,7 +99,7 @@ export function pow<B extends number>(
 export function pow<B extends number>(
   base: OperationIO<B>,
   exponent: 0.5,
-): OperationIO<Divide<B, 2>>;
+): OperationIO<DivideUnitExponents<B, 2>>;
 
 /**
  * Put a number to the power of 1.
@@ -146,7 +147,7 @@ export function pow(base: number, exponent: number): number {
  */
 export function sqrt<T extends number>(
   value: OperationIO<T>,
-): OperationIO<Divide<T, 2>> {
+): OperationIO<DivideUnitExponents<T, 2>> {
   return pow(value, 0.5);
 }
 
@@ -219,15 +220,6 @@ export function sum<T extends number>(
   return values.reduce(add<number>, 0) as OperationIO<T>;
 }
 
-/**
- * Takes the product of all the values in the given collection.
- */
-export function product<T extends number>(
-  values: ReadonlyArray<T>,
-): OperationIO<T> {
-  return values.reduce(mul<number, number>, 1) as OperationIO<T>;
-}
-
 /**
  * Equal: Compare if two values are equal.
  */