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>So what's the solution? Not having null references and having explicitly typed arrays. Throwing the baby out with the bath water. Null types are extremely use

>So what's the solution? Not having null references and having explicitly typed arrays. Throwing the baby out with the bath water. Null types are extremely useful. I don't get why the author claims the null type in C# is a form of "damage". It's just said that it's bad, not why. The problem with None in python was that you can't tell what it's supposed to be. In C# you know what type the null is meant to be.

the_af 12y ago
What are nulls extremely useful for in programming languages? At least one serious problem with nulls in many languages is that you can get one somewhere you are not expecting it, and you won't handle it correctly, resulting in an null pointer exception (if you're lucky) or a crash (if you're unlucky). That's why alternatives like Option types are so useful: you really cannot ignore them, so they won't catch you by surprise. And at the same time, you can often handle them in pretty painless ways.
aidenn0 12y ago
If you have ever programmed in a language with strict enforcement of something like a "maybe" or "option" type then you'll see that it's fairly trivial to have a separate type for a nullable pointer and a non-nullable pointer. It is essentially brain-dead that the type Foo really means "Either a Foo, or null" Failure to properly check for null is a source of many, many bugs, and there is an almost trivial way (assuming you're creating a new language, like C# was) to completely prevent it in statically typed languages that was well known when C# was invented.
- rurban 12y ago
  I don't see the issue. Armin went completely insane IMHO. This problem is usually solved by expressing the type "Foo or Null" as Foo? in such a gradually typed language. Maybe the critics should lookup the basic type literature first. Such posts will kill python. And this type of type critic already did kill python for Google. (And kept perl 10 years behind)
  - the_af 12y ago
    If when the type of a function F is "Foo or Null", you can express it as something like F(...): Foo? and if you're later forced to deal with such a value, Null cannot catch you by surprise, then haven't you just rediscovered Option types? If, on the other hand, "?" is just an operator you use on values that can be null, to guard against an exception, this seems less useful. Are you going to wrap every return value of every function call with it? What happens if you forget? How can you know, at a glance, if a function may return a null value?

the_af 12y ago

What are nulls extremely useful for in programming languages? At least one serious problem with nulls in many languages is that you can get one somewhere you are not expecting it, and you won't handle it correctly, resulting in an null pointer exception (if you're lucky) or a crash (if you're unlucky). That's why alternatives like Option types are so useful: you really cannot ignore them, so they won't catch you by surprise. And at the same time, you can often handle them in pretty painless ways.

aidenn0 12y ago

If you have ever programmed in a language with strict enforcement of something like a "maybe" or "option" type then you'll see that it's fairly trivial to have a separate type for a nullable pointer and a non-nullable pointer. It is essentially brain-dead that the type Foo really means "Either a Foo, or null" Failure to properly check for null is a source of many, many bugs, and there is an almost trivial way (assuming you're creating a new language, like C# was) to completely prevent it in statically typed languages that was well known when C# was invented.

rurban 12y ago
I don't see the issue. Armin went completely insane IMHO. This problem is usually solved by expressing the type "Foo or Null" as Foo? in such a gradually typed language. Maybe the critics should lookup the basic type literature first. Such posts will kill python. And this type of type critic already did kill python for Google. (And kept perl 10 years behind)
- the_af 12y ago
  If when the type of a function F is "Foo or Null", you can express it as something like F(...): Foo? and if you're later forced to deal with such a value, Null cannot catch you by surprise, then haven't you just rediscovered Option types? If, on the other hand, "?" is just an operator you use on values that can be null, to guard against an exception, this seems less useful. Are you going to wrap every return value of every function call with it? What happens if you forget? How can you know, at a glance, if a function may return a null value?