Like cond, but simply returns the first truthy value it encounters when executing functions in fnList against initVal. Intended for the occastions when one wants to write a cond, but the left and the right sides end up with the same function, but can also be used in any circumstance where the function being run can both serve as predicate and re…

leftCond.js

// accepts an argument object and a data object.
// first returns the value at lookupName in the data object
// and then applies the value of that back onto the data object
// treating it as meta data about the data object, eg
// lookWIthin(
//   { lookupName: 'currPage', endOfPath: ['position'] },
//   { currPage: 'page!', page!: {position: 55} }
// ) => 55
const lookWithin = ({ lookupName, endOfPath = [] }) => compose(
  apply(path),
  juxt([
    compose(
      flip(concat)(endOfPath),
      of,
      prop(lookupName)
    ),
    identity,
  ])
);

const logAdd = curry((a, b) => {
  const res = a + b;
  // console.log(res);
  return res;
});

const logAlways = (a) => (b) => {
  // console.log(`a: ${a}`);
  return a;
};

const accumApplyTo = (initVal) => (acc, fn) => applyTo(initVal, fn);

const leftCond = curry((fnList, initVal) =>
  reduceWhile(
    isNil,
    accumApplyTo(initVal),
    undefined,
    fnList
  )
);

const uistate = {
  currView: 'page2',
  page2: {sp: 100},
  page4: {sp: 200},
};

leftCond([
  always(null),
  always(null),
  always(undefined),
  lookWithin({
    lookupName: 'currView',
    endOfPath: ['sp']
  }),
  path(['subpage1', 'sp']),
  path(['subpage4', 'spx']),
  prop('currView'),
  always(0),
],
  uistate
);