go-php-serialize | Golang implementation for PHP 's function serialize | Hashing library

You're talking about the type of the variable cons, are you?

If yes, the reason its type is interface{} is because in PHP, it's possible to serialize a value of any type (from bare integer to a complicated object), and hence any deserialization code must cope with it. Since in Go the so-called "empty interface", interface{}, is satisfied by any type at all (including any custom type implemented by a programmer), it's sensbile for a decoder of PHP-serialized data to return a value of type interface{}.

After making sure decoding succeeded, you need to either type-assert the resulting value to a type you need or to use a type switch to diverge processing based on the concrete type of the value returned by the decoder.

The approach is very well demonstrated by the package you're using in its own test suite.

A snippet from it demonstrating the basic approach