package validate var ( ErrValueNotAllowed = NewError("not allowed") ) // In validates that a value equals one of the allowed values. func In[T comparable](allow ...T) func(T) error { return func(value T) error { for _, cmp := range allow { if cmp == value { return nil } } return ErrValueNotAllowed } } // NotIn validates that a value equals none of the disallowed values. func NotIn[T comparable](disallow ...T) func(T) error { return func(value T) error { for _, cmp := range disallow { if cmp == value { return ErrValueNotAllowed } } return nil } }