Three-Valued Logic

Re:Three-Valued Logic by hjjiehebebe on Friday December 15, 2017 @05:16AM (#15930826)

The problem with nulls in c++ etc. is that every reference type is forced to be nullable. There is no opt out of that semantics. You get passed in an object of type O and it is really a sum type of O + Nothing. It means you need to do runtime checks everywhere and reason across call boundaries. You need to look at he code inside that method! That so un-OO!

In Db land you can make a column not nullable. Bit the SQL languages like PLSQL TSQL etc have the same issue.

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Re:Three-Valued Logic by heavenlyblue on Friday December 15, 2017 @03:22PM (#15934755)

I would add: the reason it is a issue in C++ is because the algebra around pointers doesn’t support the NULLs explicitly:

  - the results of any operations over nulls run as if the pointer were not null
  - while anyhing you do in SQL with NULL would explicitly have a mapping to either a correct value or another NULL

This is all said knowing that it’s quite easy to understand why is that the case.

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Re:Three-Valued Logic by Sharlin on Friday December 15, 2017 @06:47AM (#15931160)

C++ references are non-nullable by design. They are sane in that regard. Pointers are nullable, of course, but at least they are syntactically conspicuous and anyway pretty rare in modern C++.

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