@extra-array/interpolate/index.js

'use strict';
function interpolate(x, fc) {
    var a = [], u, i = -1;
    for (var v of x) {
        if (++i > 0)
            a.push(fc(u, v));
        a.push(u = v);
    }
    return a;
}
module.exports = interpolate;