alt

Usage: alt([, ...keyPredForms])

Returns a regex op that returns a map entry containing the key of the first matching pred and the corresponding value. Thus the 'key' and 'val' functions can be used to refer generically to the components of the tagged return.

Source

Example:

const s = require('speculaas');
const {isBoolean, isString} = s.utils;

s.def('::bool-or-string', s.alt(':s', isString, ':b', isBoolean));

s.isValid('::bool-or-string', [true]);
// true

s.isValid('::bool-or-string', ['foo']);
// true

s.isValid('::bool-or-string', [1]);
// false