@dillonkearns/elm-graphql/examples/src/subscription/node_modules/flow-static-land/lib/Compose.js

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'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.prj = prj;
exports.inj = inj;
exports.composeFunctor = composeFunctor;
exports.composeApplicative = composeApplicative;
exports.composeFoldable = composeFoldable;
exports.composeTraversable = composeTraversable;

var _HKT = require('./HKT');

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

/*

  Functor, Applicative, Foldable, and Traversable are all closed under composition
  (Monad is not)

*/

var IsCompose = function IsCompose() {
  _classCallCheck(this, IsCompose);
}; // eslint-disable-line no-unused-vars

function prj(fga) {
  return fga;
}

function inj(fga) {
  return fga;
}

function composeFunctor(f, g) {

  function map(h, fga) {
    return inj(f.map(function (ga) {
      return g.map(h, ga);
    }, prj(fga)));
  }

  return {
    map: map
  };
}

function composeApplicative(f, g) {
  var _composeFunctor = composeFunctor(f, g),
      map = _composeFunctor.map;

  function ap(fgab, fga) {
    return inj(f.ap(f.map(function (h) {
      return function (ga) {
        return g.ap(h, ga);
      };
    }, prj(fgab)), prj(fga)));
  }

  function of(a) {
    return inj(f.of(g.of(a)));
  }

  return {
    map: map,
    ap: ap,
    of: of
  };
}

function composeFoldable(f1, f2) {

  function reduce(f, b, fa) {
    return f1.reduce(function (a, gb) {
      return f2.reduce(f, a, gb);
    }, b, prj(fa));
  }

  return {
    reduce: reduce
  };
}

function composeTraversable(t1, t2) {

  function traverse(applicative, f, ta) {
    return applicative.map(inj, t1.traverse(applicative, function (t2a) {
      return t2.traverse(applicative, f, t2a);
    }, prj(ta)));
  }

  return {
    map: composeFunctor(t1, t2).map,
    reduce: composeFoldable(t1, t2).reduce,
    traverse: traverse
  };
}