As easy as this question may seem, the answer will be as different as the number of different people or websites that you go to for an answer. It is just like asking what size dog is a medium, small or large breed. Everyone has their own opinion on what constitutes a dog that sheds based on their own experience and perception.
If you consider any dropped hair to constitute shedding then every single dog that has hair would be a shedding breed from Poodles and Groodles to Golden Retrievers and Puggles, as any dog can lose a few hairs. Most people would consider the Poodle and Poochon to be examples of non-shedding breeds as the amount of hair they lose is so minimal that most owners would not be able to find any around their home or clothes. In fact most owners would probably lose more hair than their dog! Good examples of dog breeds that do shed are the Siberian Husky and the Labrador which are known to leave a hair trail wherever they go.

Does the amount of curl in the coat determine the amount of shedding?

Yes and no. While this is a helpful guide in determining the shedding qualities of many designer breed dogs (which we will cover later), many breeds with straight hair such as the Maltese or Shih Tzu are considered to be low to non-shedding.
In many designer breeds such as Labradoodles and Groodles, the amount of curl in the coat can help to predict the shedding qualities that a puppy will have when they are an adult. These different amounts of curl are used to categorize these dogs into 3 rough groups based on their coat types, wool, fleece and hair. These coat types are not exclusive and distinct groups but more like a sliding scale with many dogs falling in between fleece to wool coat types.

What is the difference between wool, fleece and hair coat types?

Hair coats – Can be wiry in appearance like that of a wire hair Jack Russell Terrier to smooth and flat like a Labrador. Hair coated dogs will shed and have a typical dog odour but require the minimum amount of time for grooming compared to fleece and wool coats. Many first generation Groodles will possess this type of coat.
Fleece coats – Have a wavy or very loose curl appearance and have a very soft and silky feel to them and look like they are in between the hair and wool coats. They shed very little that it is usually not noticed by owners. If the dog is not groomed enough, they can shed a little more hair in the form of small hair balls that wander down the hall way. Fleece coats are a good choice for those with allergies to dog hair as they loose very little hair and are often seen on Cavoodles
Wool coats – Have a tightly curled appearance like the wool of a lamb with a thick texture. They are also considered to be a non shed coat type but all dogs regardless breed (aside from hairless breeds) will shed a few hairs from time to time. Poochons are a great example of a designer breed that will usually have a wool type coat. Wool coats are considered the best type in terms of being allergy friendly and have the best success rate with allergy prone owners. Even with this quality, no coat type can determine that a particular dog will be perfect for all allergy sufferers as allergies are an individual condition.