Idris 2 0.6.0 is now available for the JVM

Re:Idris 2 0.6.0 is now available for the JVM by harperlee on Monday February 27, 2023 @06:55AM (#34955384)

In particular, you may want this to signify “I dont know” with NULL, just as in SQL. See the Wikipedia page for ternary logic for more info.

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Re:Idris 2 0.6.0 is now available for the JVM by alexvoda on Monday February 27, 2023 @10:36AM (#34957622)

Note that 3VL (ternary logic/3 valued logic) is one of the more criticized aspects of SQL.

3VL is a gigantic leap of of complexity over 2VL (boolean). The number of possible operations is a lot higher and the choice of operations is not standardized. To quote wikipedia: "In two-valued logic there are 2 nullary operators (constants), 4 unary operators, 16 binary operators, 256 ternary operators" And we all agree which of those 16 is named what. "In three-valued logic there are 3 nullary operators (constants), 27 unary operators, 19683 binary operators, 7625597484987 ternary operators" There is no standard meaning of the 3'rd value and of the operations involving it.

That is not to say that 3VL isn't useful. I believe the reason for the criticism of 3VL in SQL it that the system made those choices for you and those choices are not always intuitive. Therefore a null in one attribute in one relation might mean something very different from a null in another attribute in another relation.

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