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either.js
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either.js
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"use strict";
var Just = require("./just.js");
var brand = {};
Left.is = LeftIs;
Right.is = RightIs;
module.exports = Object.assign(Either,{
Left, Right, of: Right, pure: Right,
unit: Right, is, fromFoldable,
});
// **************************
function Left(val) {
return LeftOrRight(val,/*isRight=*/false);
}
function LeftIs(val) {
return is(val) && !val._is_right();
}
function Right(val) {
return LeftOrRight(val,/*isRight=*/true);
}
function RightIs(val) {
return is(val) && val._is_right();
}
function Either(val) {
return LeftOrRight(val,/*isRight=*/true);
}
function LeftOrRight(val,isRight = true) {
var publicAPI = {
map, chain, flatMap: chain, bind: chain,
ap, concat, fold, _inspect, _is, _is_right,
get [Symbol.toStringTag]() {
return `Either:${isRight ? "Right" : "Left"}`;
},
};
return publicAPI;
// *********************
function map(fn) {
return (isRight ? LeftOrRight(fn(val),isRight) : publicAPI);
}
function chain(fn) {
return (isRight ? fn(val) : publicAPI);
}
function ap(m) {
return (isRight ? m.map(val) : publicAPI);
}
function concat(m) {
return (isRight ? m.map(v => val.concat(v)) : publicAPI);
}
function fold(asLeft,asRight) {
return (isRight ? asRight(val) : asLeft(val));
}
function _inspect() {
var v = Just(val)._inspect().match(/^Just\((.*)\)$/)[1];
return `${publicAPI[Symbol.toStringTag]}(${ v })`;
}
function _is(br) {
return br === brand;
}
function _is_right() {
return isRight;
}
}
function is(val) {
return val && typeof val._is == "function" && val._is(brand);
}
function fromFoldable(m) {
return m.fold(Left,Right);
}