state-monad-ts/dist/state.js

state monad in typescript

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.State = exports.unit = void 0;
exports.unit = null;
var State = /** @class */ (function () {
    function State(runState) {
        var _this = this;
        this[Symbol.toStringTag] = "StateMoand";
        this.then = this.bind;
        this.runState = runState;
        this.execState = function (s) { return _this.runState(s)[1]; };
        this.evalState = function (s) { return _this.runState(s)[0]; };
    }
    State.prototype.map = function (f) {
        var _this = this;
        var runState = function (s) {
            var _a = _this.runState(s), a = _a[0], s1 = _a[1];
            var b = f(a);
            return [b, s1];
        };
        return new State(runState);
    };
    State.pure = function (a) {
        var runState = function (s) { return [a, s]; };
        return new State(runState);
    };
    State.prototype.ap = function (fa) {
        var _this = this;
        var runState = function (s) {
            var _a = fa.runState(s), f = _a[0], s1 = _a[1];
            var _b = _this.runState(s1), a = _b[0], s2 = _b[1];
            return [f(a), s2];
        };
        return new State(runState);
    };
    State.prototype.bind = function (f) {
        var _this = this;
        var runState = function (s) {
            var _a = _this.runState(s), a = _a[0], s1 = _a[1];
            return f(a).runState(s1);
        };
        return new State(runState);
    };
    State.prototype.get = function () {
        return this;
    };
    State.prototype.put = function (s) {
        return new State(function () { return [exports.unit, s]; });
    };
    State.prototype.modify = function (f) {
        return new State(function (s) { return [exports.unit, f(s)]; });
    };
    State.return = State.pure;
    return State;
}());
exports.State = State;