47 lines
2.2 KiB
JavaScript
47 lines
2.2 KiB
JavaScript
// This module ensures that we never accidentally create more than one JS object for the same type twice.
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// We do so by creating (nested) DefaultMap(s) for all non-nullary type constructors
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// It is a cheap workaround for JS lacking customizable hash-functions and equality-testing-functions.
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import { Function } from "./metacircular.js";
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import { DefaultMap } from "./util.js";
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const listTypeRegistry = new DefaultMap(elementType => ({listOf: elementType}));
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const genericTypeRegistry = new DefaultMap(underlyingType => ({generic: underlyingType}));
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const fnTypeRegistry = new DefaultMap(inType => new DefaultMap(outType => ({in: inType, out: outType})));
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const productTypeRegistry = new DefaultMap(leftType => new DefaultMap(rightType => ({operator: "product", leftType, rightType})));
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const sumTypeRegistry = new DefaultMap(leftType => new DefaultMap(rightType => ({operator: "sum", leftType, rightType})));
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export const lsType = listTypeRegistry.getdefault.bind(listTypeRegistry);
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export const genericType = genericTypeRegistry.getdefault.bind(genericTypeRegistry);
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export const fnType = ({in: inType, out: outType}) => fnTypeRegistry.getdefault(inType, true).getdefault(outType, true);
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export const sumType = (leftType, rightType) => sumTypeRegistry.getdefault(leftType, true).getdefault(rightType, true);
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export const prodType = (leftType, rightType) => productTypeRegistry.getdefault(leftType, true).getdefault(rightType, true);
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// Wrapper around function below.
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export const typedFnType = (instance, callback) => {
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const [t, typesOfFns] = typedFnType2(callback);
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const res = [
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{i: instance, t},
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...typesOfFns,
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];
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return res;
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}
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// Create a function type, and also create Type-links for the function type (being typed by Function) and for all the nested function types. Saves a lot of code writing.
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export const typedFnType2 = callback => {
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const fnTs = [];
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const wrappedFnType = ({in: inType, out: outType}) => {
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console.log('wrappedFnType called')
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const fnT = fnType({in: inType, out: outType});
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fnTs.push(fnT);
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return fnT;
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}
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const t = callback(wrappedFnType); // force evaluation
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return [
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t,
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fnTs.map(fnT => ({i: fnT, t: Function})),
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];
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}
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