pragmatic-fp-ts/lib/multimethod.js

Opinionated functional programming library with easy use in mind

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.defmethod = exports.defmulti = exports.MultiMethod = void 0;
class MultiMethod extends Function {
    constructor(dispatch) {
        super();
        const methods = {};
        const multi = function (...args) {
            const dispatchKey = dispatch(...args);
            const method = methods[dispatchKey] || methods.default;
            if (!method) {
                throw new Error(`No method implementation for dispatch key ${dispatchKey}`);
            }
            return method(...args);
        };
        multi.defmethod = (dispatchKey, method) => {
            if (methods[dispatchKey]) {
                console.warn(`Overriding definition of ${dispatchKey}`);
            }
            methods[dispatchKey] = method;
        };
        return multi;
    }
}
exports.MultiMethod = MultiMethod;
function defmulti(dispatch) {
    return new MultiMethod(dispatch);
}
exports.defmulti = defmulti;
function defmethod(multimethod, dispatchResult, impl) {
    if (!multimethod.defmethod) {
        throw new Error(`Can not extend given method: not a multi method`);
    }
    multimethod.defmethod(dispatchResult, impl);
}
exports.defmethod = defmethod;