65 lines
1.9 KiB
JavaScript
65 lines
1.9 KiB
JavaScript
import { Unit } from "../primitives/types.js";
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import { unit } from "../primitives/unit.js";
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import { capitalizeFirstLetter } from "../util/util.js";
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import { newProduct, getLeft, getRight } from "./product.js";
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import { fnType, prodType } from "./types.js";
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// 'fields' is an array of (name: string, type: Type) pairs.
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// e.g.:
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// [{l: "x", r: Double}, {l: "y", r: Double}]
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// results in the type (Double × (Double × Unit))
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export const structType = fields => {
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if (fields.length === 0) {
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return Unit;
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}
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const [field, ...rest] = fields;
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const fieldType = getRight(field);
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return prodType(fieldType)(structType(rest));
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};
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export const makeConstructor = fields => {
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const internal = (nParams, ret) => {
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if (nParams === 0) {
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const result = ret(unit);
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return result;
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}
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return nextParam => {
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const wrappedName = 'wrapped_' + ret.name;
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const newRet = {
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[wrappedName]: inner => newProduct(nextParam)(ret(inner)),
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}[wrappedName];
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return internal(nParams-1, newRet);
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}
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};
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const id = x => x;
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return internal(fields.length, id);
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};
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export const makeConstructorType = type => fields => {
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if (fields.length === 0) {
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return type;
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}
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const [field, ...rest] = fields;
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const fieldType = getRight(field);
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return fnType(fieldType)(makeConstructorType(rest));
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};
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export const makeGetters = fields => {
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if (fields.length === 0) {
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return [];
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}
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const [field, ...rest] = fields;
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const fieldName = getLeft(field);
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const getterName = `get${capitalizeFirstLetter(fieldName)}`;
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return [
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{ [getterName]: obj => getLeft(obj) }[getterName],
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...makeGetters(rest).map(getter => ({[getter.name]: obj => getter(getRight(obj))}[getter.name])),
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];
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};
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export const makeGettersTypes = type => fields => {
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return fields.map(field => {
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const fieldType = getRight(field);
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return fnType(type)(fieldType);
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});
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};
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