📝 Bind the handler-map function in every example

Each README and JSDoc example now assigns the function that takes the
handler object (the factory result, or the tagged key step) to a match…
variable and reuses it, so the builder is created once instead of per
call.
This commit is contained in:
tmu committed 2026-09-23 22:33:43 +00:00
1 parent c8bee95088
commit c878e60ff2
3 files changed
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@@ -37,6 +37,9 @@ The package exports four factories. Two axes pick one:
| `getTaggedUnionMatcher<T>()` | the value is a discriminated object and all handlers return the same type | one common `R` |
| `getTaggedUnionMatcherW<T>()` | the value is a discriminated object and handlers return different types | union of the handlers |
Bind the function that takes the handler map to a `match…` variable once and
reuse it; the examples below do this, so the builder is allocated once.
### Primitive-union matchers
`getPrimitiveUnionMatcher<T>()` takes the finite universe `T` and returns a
@@ -46,7 +49,9 @@ matcher: a function from `T` to the common return type.
```ts
import { getPrimitiveUnionMatcher } from "tiny-pattern-ts";
const reply = getPrimitiveUnionMatcher<"yes" | "no">()({
const matchAnswer = getPrimitiveUnionMatcher<"yes" | "no">();
const reply = matchAnswer({
yes: () => "agreed",
no: () => "declined",
});
@@ -58,7 +63,9 @@ Add a fallback as the second argument to leave members unhandled; the fallback
receives the remainder:
```ts
const label = getPrimitiveUnionMatcher<"yes" | "no" | "maybe">()(
const matchLabel = getPrimitiveUnionMatcher<"yes" | "no" | "maybe">();
const label = matchLabel(
{ yes: () => "agreed", no: () => "declined" },
(other) => `not sure: ${other}`, // other: "maybe"
);
@@ -79,7 +86,9 @@ import { getTaggedUnionMatcher } from "tiny-pattern-ts";
type Shape =
{ kind: "circle"; radius: number } | { kind: "square"; side: number };
const area = getTaggedUnionMatcher<Shape>()("kind")({
const matchShape = getTaggedUnionMatcher<Shape>()("kind");
const area = matchShape({
circle: (s) => Math.PI * s.radius ** 2,
square: (s) => s.side ** 2,
});
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@@ -111,7 +111,8 @@ const dispatch =
* @typeParam T - The finite universe of primitive members to match.
* @returns A builder for the handler map, or the handler map plus a fallback.
* @example
* const describe = getPrimitiveUnionMatcher<"yes" | "no">()({
* const matchAnswer = getPrimitiveUnionMatcher<"yes" | "no">();
* const describe = matchAnswer({
* yes: () => "agreed",
* no: () => "declined",
* });
@@ -133,7 +134,8 @@ export const getPrimitiveUnionMatcher = <
* @typeParam T - The finite universe of primitive members to match.
* @returns A builder for the handler map, or the handler map plus a fallback.
* @example
* const reply = getPrimitiveUnionMatcherW<"yes" | "no">()({
* const matchReply = getPrimitiveUnionMatcherW<"yes" | "no">();
* const reply = matchReply({
* yes: () => 1,
* no: () => "declined",
* });
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@@ -173,7 +173,8 @@ const dispatch =
* | { kind: "circle"; radius: number }
* | { kind: "square"; side: number };
*
* const area = getTaggedUnionMatcher<Shape>()("kind")({
* const matchShape = getTaggedUnionMatcher<Shape>()("kind");
* const area = matchShape({
* circle: (s) => Math.PI * s.radius ** 2,
* square: (s) => s.side ** 2,
* });
@@ -194,7 +195,8 @@ export const getTaggedUnionMatcher = <
* @typeParam T - The discriminated-union type to match.
* @returns A function that takes the discriminant property's name.
* @example
* const describe = getTaggedUnionMatcherW<Shape>()("kind")({
* const matchShape = getTaggedUnionMatcherW<Shape>()("kind");
* const describe = matchShape({
* circle: () => "round",
* square: () => 4,
* });