null — the null sentinel

github.com/go-composites/null (Go package Null, imported from the src/ sub-directory) is the org's minimal null value. It is a leaf module with no dependencies.

API

import Null "github.com/go-composites/null/src"

type Interface interface{}

func New() Interface

Null.Interface is the empty interface — any value satisfies it. New() returns an internal *data struct (which carries no fields).

The concrete value also has a method:

func (d data) IsNul() bool // always returns true

IsNul is unexported in effect

IsNul() is spelled without the trailing l ("IsNul", not "IsNull") and is not part of Null.Interface (which is interface{}). Because the concrete data type is unexported, callers holding a Null.Interface cannot invoke IsNul() without a type assertion to the package-private type, which is impossible from outside the package. In practice the value is used purely as an opaque non-nil placeholder.

Where it is used

result installs Null.New() as the default payload of a freshly built Result, so that Payload() never returns a bare nil:

r := Result.New()
r.Payload() // a non-nil Null value, not nil