37 lines
1.1 KiB
JavaScript
37 lines
1.1 KiB
JavaScript
import { capitalizeFirstLetter } from "../util/util.js";
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import { newProduct as newProduct, getLeft } from "./product.js";
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import { newLeft, newRight, match } from "./sum.js";
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const eatParameters = (numParams, result) => {
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if (numParams === 0) {
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return result;
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}
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else return () => eatParameters(numParams-1, result);
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}
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export const makeMatchFn = variants => {
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if (variants.length === 0) {
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return undefined;
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}
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const [_, ...remainingVariants] = variants;
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return sum => handler => {
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return match(sum)
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(leftValue => eatParameters(remainingVariants.length, handler(leftValue)))
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(rightValue => makeMatchFn(remainingVariants)(rightValue));
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};
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};
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export const makeConstructors = variants => {
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if (variants.length === 0) {
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return [];
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}
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const [variant, ...remainingVariants] = variants;
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const name = getLeft(variant);
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const ctorName = `new${capitalizeFirstLetter(name)}`;
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const constructor = { [ctorName]: val => newLeft(val) }[ctorName];
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return [
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constructor,
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...makeConstructors(remainingVariants).map(ctor =>
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({[ctor.name]: val => newRight(ctor(val))}[ctor.name])),
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];
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}
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