unless.js•1.19 kB
var _curry3 = require('./internal/_curry3');
/**
* Tests the final argument by passing it to the given predicate function. If
* the predicate is not satisfied, the function will return the result of
* calling the `whenFalseFn` function with the same argument. If the predicate
* is satisfied, the argument is returned as is.
*
* @func
* @memberOf R
* @since v0.18.0
* @category Logic
* @sig (a -> Boolean) -> (a -> a) -> a -> a
* @param {Function} pred A predicate function
* @param {Function} whenFalseFn A function to invoke when the `pred` evaluates
* to a falsy value.
* @param {*} x An object to test with the `pred` function and
* pass to `whenFalseFn` if necessary.
* @return {*} Either `x` or the result of applying `x` to `whenFalseFn`.
* @see R.ifElse, R.when
* @example
*
* // coerceArray :: (a|[a]) -> [a]
* var coerceArray = R.unless(R.isArrayLike, R.of);
* coerceArray([1, 2, 3]); //=> [1, 2, 3]
* coerceArray(1); //=> [1]
*/
module.exports = _curry3(function unless(pred, whenFalseFn, x) {
return pred(x) ? x : whenFalseFn(x);
});