fix(vx-scale): make bandScale domain Generic

packages/vx-scale/src/scales/band.ts

@@ -1,15 +1,15 @@
 import { scaleBand } from 'd3-scale';
 
-type Domain = string | { valueOf(): string };
-type Range = number | { valueOf(): number };
+type StringLike = string | { valueOf(): string };
+type Numeric = number | { valueOf(): number };
 
-export type BandConfig = {
+export type BandConfig<Datum extends StringLike> = {
   /** Sets the output values of the scale, which are numbers for band scales. */
-  range?: [Range, Range];
+  range?: [Numeric, Numeric];
   /** Sets the output values of the scale while setting its interpolator to round. If the elements are not numbers, they will be coerced to numbers. */
-  rangeRound?: [Range, Range];
+  rangeRound?: [Numeric, Numeric];
   /** Sets the input values of the scale, which are strings for band scales. */
-  domain?: Domain[];
+  domain?: Datum[];
   /** 0-1, determines how any leftover unused space in the range is distributed. 0.5 distributes it equally left and right. */
   align?: number;
   /** 0-1, determines the ratio of the range that is reserved for blank space before the first point and after the last. */
@@ -21,7 +21,7 @@ export type BandConfig = {
   tickFormat?: unknown;
 };
 
-export default ({
+export default function bandScale<Datum extends StringLike = StringLike>({
   range,
   rangeRound,
   domain,
@@ -30,8 +30,8 @@ export default ({
   paddingOuter,
   align,
   tickFormat,
-}: BandConfig) => {
-  const scale = scaleBand<Domain>();
+}: BandConfig<Datum>) {
+  const scale = scaleBand<Datum>();
 
   if (range) scale.range(range);
   if (rangeRound) scale.rangeRound(rangeRound);
@@ -48,4 +48,4 @@ export default ({
   scale.type = 'band';
 
   return scale;
-};
+}