Topic: data type compatibility

Summary

Two types may be compatible if they have the same name, have the same definition, share the same qualifying rights, or share the same defined operations. Type compatibility by type definition makes type checking representation dependent, but widens the range of accepted types. An alternative is compatibility of representation types, e.g., 16-bit integers.

Type compatibility may mean identical type identifiers, intersecting type attributes, or convertible types. Type compatibility may be complicated when variables belong to many types. For instance, a procedure may take any argument with a name and birthday component. (cbb 5/80)

Subtopic: type compatibility

Quote: a constant is type compatible if it can be a value of that type; it can be compatible with many types [»clayR4_1978]

Quote: a reference type conforms with a variable if it is a reference to the mode of the variable [»bekiH_1971, OK]

Subtopic: qualifying rights

Quote: changing the qualifying rights for an element of a data structure changes its type [»joneAK4_1976, OK]

Subtopic: mutable vs. immutable

Quote: mutable objects are the same only if they are the same object [»liskBH2_1976, OK]

Subtopic: representation type

Quote: a rep-type is the set of modes with the same representation; explicitly declared, includes operations [»parnDL3_1976]

Related Topics

Group: data type   (34 topics, 730 quotes)
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Topic: structural equivalence vs. name equivalence of data types (30 items)
Topic: type conversion
(33 items)