904:
it visible when such facilities are used. Unfortunately, this was not consequently implemented in the original language report and its implementation. There still remained unsafe facilities such as the type cast syntax and variant records (inherited from Pascal) that could be used without prior import. The difficulty in moving these facilities into the SYSTEM pseudo-module was the lack of any identifier for the facility that could then be imported since only identifiers can be imported, but not syntax.
204:. Type safety is sometimes alternatively considered to be a property of facilities of a computer language; that is, some facilities are type-safe and their usage will not result in type errors, while other facilities in the same language may be type-unsafe and a program using them may encounter type errors. The behaviors classified as type errors by a given programming language are usually those that result from attempts to perform operations on
1133:
records) or moved to pseudo-module UNSAFE. For facilities where there is no identifier that could be imported, enabling identifiers were introduced. In order to enable such a facility, its corresponding enabling identifier must be imported from pseudo-module UNSAFE. No unsafe facilities remain in the language that do not require import from UNSAFE.
717:, which tells the function to expect a pointer to a character-string and yet supplies an integer argument, may be accepted by compilers, but will produce undefined results.) This is partially mitigated by some compilers (such as gcc) checking type correspondences between printf arguments and format strings.
1409:
is a type-safe language. A Common Lisp compiler is responsible for inserting dynamic checks for operations whose type safety cannot be proven statically. However, a programmer may indicate that a program should be compiled with a lower level of dynamic type-checking. A program compiled in such a mode
859:
Sometimes a part of the type safety is implemented indirectly: e.g. the class BigDecimal represents a floating point number of arbitrary precision, but handles only numbers that can be expressed with a finite representation. The operation BigDecimal.divide() calculates a new object as the division of
346:
In isolation, type soundness is a relatively weak property, as it essentially just states that the rules of a type system are internally consistent and cannot be subverted. However, in practice, programming languages are designed so that well-typedness also entails other, stronger properties, some of
903:
Modula-2 is a strongly-typed language with a design philosophy to require any unsafe facilities to be explicitly marked as unsafe. This is achieved by "moving" such facilities into a built-in pseudo-library called SYSTEM from where they must be imported before they can be used. The import thus makes
1132:
A recent revision of the language applied the original design philosophy rigorously. First, pseudo-module SYSTEM was renamed to UNSAFE to make the unsafe nature of facilities imported from there more explicit. Then all remaining unsafe facilities where either removed altogether (for example variant
863:
In this case if the division has no finite representation, as when one computes e.g. 1/3=0.33333..., the divide() method can raise an exception if no rounding mode is defined for the operation. Hence the library, rather than the language, guarantees that the object respects the contract implicit in
797:
is type-safe. It has support for untyped pointers, but this must be accessed using the "unsafe" keyword which can be prohibited at the compiler level. It has inherent support for run-time cast validation. Casts can be validated by using the "as" keyword that will return a null reference if the cast
1241:
has had a number of type safety requirements, some of which are kept in some compilers. Where a Pascal compiler dictates "strict typing", two variables cannot be assigned to each other unless they are either compatible (such as conversion of integer to real) or assigned to the identical subtype.
720:
In addition, C, like Ada, provides unspecified or undefined explicit conversions; and unlike in Ada, idioms that use these conversions are very common, and have helped to give C a type-unsafe reputation. For example, the standard way to allocate memory on the heap is to invoke a memory allocation
1818:
The two child classes have members of different types. When downcasting a parent class pointer to a child class pointer, then the resulting pointer may not point to a valid object of correct type. In the example, this leads to garbage value being printed. The problem could have been avoided by
1055:
The ISO Modula-2 standard corrected this for the type cast facility by changing the type cast syntax into a function called CAST which has to be imported from pseudo-module SYSTEM. However, other unsafe facilities such as variant records remained available without any import from pseudo-module
700:
is type-safe in limited contexts; for example, a compile-time error is generated when an attempt is made to convert a pointer to one type of structure to a pointer to another type of structure, unless an explicit cast is used. However, a number of very common operations are non-type-safe; for
465:
and Zilles defined a strongly-typed language as one in which "whenever an object is passed from a calling function to a called function, its type must be compatible with the type declared in the called function." In 1977, Jackson wrote, "In a strongly typed language each data area will have a
561:
defined by programmers even when this is not strictly necessary for memory safety or for the prevention of any kind of catastrophic failure. Allocations are given a type describing its contents, and this type is fixed for the duration of the allocation. This allows type-based
273:, then expressions accepted by that type system must evaluate to a value of the appropriate type (rather than produce a value of some other, unrelated type or crash with a type error). Vijay Saraswat provides the following, related definition:
619:, will adhere to that contract: hence in that function the operations permitted on that object will be only those defined by the methods of the class the object implements. This will guarantee that the object integrity will be preserved.
1543:
explicitly prevents the compiler from performing a safe conversion from integer to floating-point value. When the program runs it will output a garbage floating-point value. The problem could have been avoided by instead writing
415:) proposed in academic programming language research. Many languages, on the other hand, are too big for human-generated type safety proofs, as they often require checking thousands of cases. Nevertheless, some languages such as
466:
distinct type and each process will state its communication requirements in terms of these types." In contrast, a weakly typed language may produce unpredictable results or may perform implicit type conversion.
289:, which are specific to each programming language. Consequently, a precise, formal definition of type soundness depends upon the style of formal semantics used to specify a language. In 1994, Andrew Wright and
401:
of different types. For instance, inches and millimeters may both be stored as integers, but should not be substituted for each other or added. A type system can enforce two different types of integer for
297:, which is closest to the notion of type safety as understood by most programmers. Under this approach, the semantics of a language must have the following two properties to be considered type-sound:
654:, but also to encourage type-safe programming. To resolve these conflicting goals, Ada confines type-unsafety to a certain set of special constructs whose names usually begin with the string
731:), which the calling code must explicitly or implicitly cast to the appropriate pointer type. Pre-standardized implementations of C required an explicit cast to do so, therefore the code
234:
and consulting them as needed to detect imminent errors, or a combination of both. Dynamic type enforcement often allows programs to run that would be invalid under static enforcement.
809:
type (from which all other types are derived) runs the risk of defeating the purpose of the C# type system. It is usually better practice to abandon object references in favour of
1418:
The following examples illustrates how C++ cast operators can break type safety when used incorrectly. The first example shows how basic data types can be incorrectly cast:
2105:
573:. Pierce says, "it is extremely difficult to achieve type safety in the presence of an explicit deallocation operation", due to the dangling pointer problem. However
312:
or can be reduced towards a value in some well-defined way. In other words, the program never gets into an undefined state where no further transitions are possible.
461:
Programming languages are often colloquially classified as strongly typed or weakly typed (also loosely typed) to refer to certain aspects of type safety. In 1974,
544:
520:
496:
2249:
Type safety is hence also a matter of good class definition: public methods that modify the internal state of an object shall preserve the object itegrity
431:, used to "escape" from the usual restricted environment in which I/O is possible, circumvents the type system and so can be used to break type safety.)
546:, causing a type error when the variable is read. Conversely, if the language is memory-safe, it cannot allow an arbitrary integer to be used as a
237:
In the context of static (compile-time) type systems, type safety usually involves (among other things) a guarantee that the eventual value of any
2298:
In C, the proper method is to declare that malloc returns a pointer to void, then explicitly coerce the pointer into the desired type with a cast.
443:
written in other languages; such errors could render a given implementation type unsafe in certain circumstances. An early version of Sun's
277:
A language is type-safe if the only operations that can be performed on data in the language are those sanctioned by the type of the data.
2204:
2113:
880:
435:
is another example of such an "escape" feature. Regardless of the properties of the language definition, certain errors may occur at
241:
will be a legitimate member of that expression's static type. The precise requirement is more subtle than this — see, for example,
891:
to interact with non-ML code (such as C libraries) that may require data laid out in specific ways. Another example is the SML/NJ
419:, which has rigorously defined semantics, have been proved to meet one definition of type safety. Some other languages such as
171:
2451:
2291:
887:, provide libraries that offer unsafe operations. These facilities are often used in conjunction with those implementations'
570:
61:
2542:
1856:
1381:(because they are not identical, even though the components of that user defined type are identical) and an assignment of
622:
Exceptions to this are object oriented languages that allow dynamic modification of the object structure, or the use of
436:
231:
2234:
2188:
2069:
2054:
Proceedings of the 7th ACM SIGPLAN International
Workshop on Libraries, Languages and Compilers for Array Programming
810:
577:
is generally considered type-safe and uses a borrow checker to achieve memory safety, instead of garbage collection.
2328:
335:
356:
246:
2007:
794:
547:
427:
to meet some definition of type safety, provided certain "escape" features are not used (for example
Haskell's
420:
293:
formulated what has become the standard definition and proof technique for type safety in languages defined by
1925:
1907:
1238:
623:
305:
673:
is a subset of Ada eliminating all its potential ambiguities and insecurities while at the same time adding
838:
616:
378:
that could otherwise arise from a pointer to one type of object being treated as a pointer to another type.
727:, with an argument indicating how many bytes are required. The function returns an untyped pointer (type
626:
to modify the content of an object to overcome the constraints imposed by the class methods definitions.
574:
281:
However, what precisely it means for a program to be "well typed" or to "go wrong" are properties of its
875:
has rigorously defined semantics and is known to be type-safe. However, some implementations, including
888:
670:
440:
220:
when there's no definition on how to handle this case. This classification is partly based on opinion.
217:
164:
2370:
1992:
Proceedings of the 9th ACM SIGPLAN-SIGACT symposium on
Principles of programming languages - POPL '82
876:
834:
826:
360:
213:
135:
2148:
799:
697:
639:
597:
309:
238:
205:
798:
is invalid, or by using a C-style cast that will throw an exception if the cast is invalid. See
666:
constructs very carefully and only when necessary; programs that do not use them are type-safe.
2143:
782:
763:
615:
Each function that exchanges objects derived from a specific class, or implementing a specific
523:
456:
331:
322:
After each evaluation step, the type of each expression remains the same (that is, its type is
79:
41:
2283:
2268:
57:
2391:
776:
294:
157:
110:
806:
2547:
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892:
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to the language itself (in form of pre-, and post-conditions, as well as type invariants).
444:
330:
A number of other formal treatments of type soundness have also been published in terms of
197:
601:
8:
2412:
853:
502:
memory error allows writing a bit pattern that does not represent a legitimate member of
75:
2521:
2474:
2437:
2075:
2013:
685:
674:
658:. Unchecked_Deallocation can be effectively banned from a unit of Ada text by applying
651:
558:
529:
505:
481:
351:
Prevention of illegal operations. For example, a type system can reject the expression
290:
2478:
2447:
2287:
2230:
2184:
2079:
2065:
2003:
1968:
1897:
849:
412:
316:
286:
120:
2525:
2017:
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across allocations of different types. But most languages enforce the proper use of
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2490:
2176:
2153:
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1995:
1958:
1902:
1892:
814:
678:
554:
499:
282:
223:
185:
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itself, which must use unsafe operations to execute ML code entered by the user.
643:
586:
386:
140:
130:
66:
2263:
1987:
563:
462:
382:
115:
105:
70:
779:
cannot be implicitly converted to or from integers or other enumeration types.
2536:
2279:
2171:
Jackson, K. (1977). "Parallel processing and modular software construction".
1972:
647:
475:
369:
125:
100:
2517:
2061:
2495:
2441:
1963:
1946:
1857:"What to know before debating type systems | Ovid [blogs.perl.org]"
770:
432:
375:
258:
227:
145:
2205:"CS1130. Transition to OO programming. – Spring 2012 --self-paced version"
2157:
1999:
1550:
The next example shows how object references can be incorrectly downcast:
1836:
1406:
872:
752:
590:
416:
394:
84:
22:
2032:
600:
essentially defines the structure of the objects derived from it and an
2180:
201:
1883:
Milner, Robin (1978), "A Theory of Type
Polymorphism in Programming",
608:
for handling these objects. Each time a new object is created it will
478:. For instance, in an implementation of a language that has some type
2175:. Lecture Notes in Computer Science. Vol. 54. pp. 436–443.
2134:
Liskov, B; Zilles, S (1974). "Programming with abstract data types".
398:
242:
209:
385:, can detect and reject out-of-bound accesses, preventing potential
2461:
1222:(* enabling identifier for foreign function interface facility *)
783:
C++ explicit constructors and C++11 explicit conversion operators
677:
to the language features available. SPARK avoids the issues with
363:
2092:
411:
Type safety is usually a requirement for any toy language (i.e.
756:
734:
723:
593:
is in place. This is expressed in terms of class definitions.
589:
languages type safety is usually intrinsic in the fact that a
16:
Extent to which a programming language discourages type errors
2323:
2321:
884:
755:
operator returns a pointer of type based on operand, whereas
701:
example, the usual way to print an integer is something like
553:
As a minimal condition, a type-safe language must not allow
550:, hence there must be a separate pointer or reference type.
713:
at run-time to expect an integer argument. (Something like
629:
580:
566:
to infer that allocations of different types are distinct.
2318:
2258:
2207:. Cornell University, Department of Computer Science. 2005
984:(* but type cast syntax can be used without such import *)
381:
More sophisticated type systems, such as those supporting
230:, or dynamic, associating type information with values at
1994:. Association for Computing Machinery. pp. 207–212.
2472:
1938:
1389:
would be legal because the subtypes they are defined to
662:
to this unit. It is expected that programmers will use
747:
Some features of C++ that promote more type-safe code:
2056:. Association for Computing Machinery. pp. 1–14.
1242:
For example, if you have the following code fragment:
829:
is designed to enforce type safety. Anything in Java
406:
532:
508:
484:
2504:
Macrakis, Stavros (April 1982). "Safety and power".
2050:"Towards size-dependent types for array programming"
2034:
Operational
Semantics and Polymorphic Type Inference
848:
enforcement, each object, before usage, needs to be
469:
341:
2267:
2173:Design and Implementation of Programming Languages
2048:Henriksen, Troels; Elsman, Martin (17 June 2021).
918:(* allows the use of certain unsafe facilities: *)
538:
514:
490:
1945:Wright, A. K.; Felleisen, M. (15 November 1994).
1908:20.500.11820/d16745d7-f113-44f0-a7a3-687c2b709f66
498:which allows some bit patterns but not others, a
2534:
2392:"reinterpret_cast conversion - cppreference.com"
1988:"Principal type-schemes for functional programs"
1228:(* pragma for foreign function interface to C *)
681:by disallowing allocation at run time entirely.
439:due to bugs in the implementation, or in linked
2047:
1944:
1919:
1917:
304:A well-typed program never gets "stuck": every
2329:"The Separation of Safe and Unsafe Facilities"
1986:Damas, Luis; Milner, Robin (25 January 1982).
766:to achieve polymorphism without void pointers.
2309:
1878:
1876:
165:
2413:"dynamic_cast conversion - cppreference.com"
2229:. Cambridge, Mass.: MIT Press. p. 158.
2133:
1914:
856:but only inside properly allocated objects.
226:can be static, catching potential errors at
1985:
1827:that throws an exception on invalid casts.
1393:identical. However, an assignment such as
1369:Under strict typing, a variable defined as
257:Intuitively, type soundness is captured by
1873:
172:
158:
2494:
2147:
1962:
1906:
1896:
1204:(* Type cast in Modula-2 Revision 2010 *)
450:
2503:
2479:"A Syntactic Approach to Type Soundness"
1947:"A Syntactic Approach to Type Soundness"
1923:
630:Type safety issues in specific languages
581:Type safety in object oriented languages
447:was vulnerable to this sort of problem.
2170:
1885:Journal of Computer and System Sciences
762:C++ code can use virtual functions and
2535:
2506:ACM SIGSOFT Software Engineering Notes
2436:
2224:
1882:
265:Well-typed programs cannot "go wrong".
2095:. Smlnj.org. Retrieved on 2013-11-02.
2030:
860:two numbers expressed as BigDecimal.
773:that performs run-time type checking.
837:and each object is an instance of a
269:In other words, if a type system is
2252:
407:Type-safe and type-unsafe languages
13:
2110:GHC libraries manual: base-3.0.1.0
813:, similar to templates in C++ and
785:prevent implicit type conversions.
14:
2559:
2350:"ISO Modula-2 Language Reference"
777:C++11 strongly-typed enumerations
769:Safer casting operators, such as
474:Type safety is closely linked to
470:Memory management and type safety
355:as invalid, because the division
342:Relation to other forms of safety
2466:Portland Pattern Repository Wiki
1410:cannot be considered type-safe.
879:(SML/NJ), its syntactic variant
642:was designed to be suitable for
336:structural operational semantics
208:that are not of the appropriate
2443:Types and Programming Languages
2405:
2384:
2363:
2342:
2303:
2243:
2227:Types and programming languages
2218:
2197:
2164:
2127:
1413:
1127:(* Type cast in ISO Modula-2 *)
2098:
2086:
2041:
2024:
1979:
1924:Saraswat, Vijay (1997-08-15).
1849:
1603:// virtual destructor for RTTI
1400:
1385:is illegal. An assignment of
867:
739:became the accepted practice.
252:
1:
2430:
569:Most type-safe languages use
2225:Pierce, Benjamin C. (2002).
1898:10.1016/0022-0000(78)90014-4
800:C Sharp conversion operators
686:statically checked contracts
675:statically checked contracts
7:
2543:Programming language topics
2483:Information and Computation
1951:Information and Computation
1830:
1801:// will output garbage data
1225:<*FFI="C"*>
898:
889:foreign function interfaces
10:
2564:
2270:The C Programming Language
1522:// output integer as float
1501:// reinterpret bit pattern
671:SPARK programming language
454:
196:are the extent to which a
1233:
877:Standard ML of New Jersey
374:Type systems can prevent
1842:
1552:
1420:
1244:
1135:
1058:
906:
261:'s pithy statement that
200:discourages or prevents
2518:10.1145/1005937.1005941
2371:"Common Lisp HyperSpec"
2312:Programming in Modula-2
2062:10.1145/3460944.3464310
1926:"Java is not type-safe"
852:. Java allows usage of
820:
759:returns a void pointer.
2496:10.1006/inco.1994.1093
2310:Niklaus Wirth (1985).
1964:10.1006/inco.1994.1093
864:the class definition.
805:Undue reliance on the
742:
733:(struct foo *) malloc(
698:C programming language
634:
540:
516:
492:
457:Strong and weak typing
451:Strong and weak typing
332:denotational semantics
42:Strong vs. weak typing
2415:. En.cppreference.com
2394:. En.cppreference.com
2158:10.1145/942572.807045
2000:10.1145/582153.582176
1738:// upcast always safe
789:
541:
517:
493:
359:is not defined for a
295:operational semantics
2276:Englewood Cliffs, NJ
2031:Tofte, Mads (1988).
893:interactive toplevel
691:
612:with that contract.
530:
506:
482:
445:Java virtual machine
308:is either already a
198:programming language
2473:Wright, Andrew K.;
2438:Pierce, Benjamin C.
2136:ACM SIGPLAN Notices
1774:// invalid downcast
650:and other forms of
559:abstract data types
397:originating in the
249:for complications.
2475:Matthias Felleisen
2314:. Springer Verlag.
2181:10.1007/BFb0021435
2106:"System.IO.Unsafe"
1546:float fval = ival;
1395:T1.Q := D1.Q;
721:function, such as
652:system programming
571:garbage collection
536:
512:
488:
353:3 / "Hello, World"
291:Matthias Felleisen
2453:978-0-262-16209-8
2293:978-0-13-110362-7
2264:Dennis M. Ritchie
1539:In this example,
844:To implement the
679:dangling pointers
555:dangling pointers
539:{\displaystyle t}
515:{\displaystyle t}
491:{\displaystyle t}
413:esoteric language
317:subject reduction
315:Preservation (or
287:dynamic semantics
212:, e.g., adding a
182:
181:
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2274:(2nd ed.).
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2112:. Archived from
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1558:<iostream>
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1480:reinterpret_cast
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1468:// integer value
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1448:
1445:
1442:
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1427:
1426:<iostream>
1424:
1397:would be legal.
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712:
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665:
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500:dangling pointer
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224:Type enforcement
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29:General concepts
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854:primitive types
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429:unsafePerformIO
428:
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383:dependent types
352:
347:which include:
344:
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17:
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5:
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2008:
1978:
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1913:
1891:(3): 348–375,
1872:
1861:blogs.perl.org
1847:
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1399:
1387:T1 := T2;
1383:T1 := D2;
1375:not compatible
1245:
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648:device drivers
636:
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564:alias analysis
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455:Main article:
452:
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194:type soundness
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2446:. MIT Press.
2445:
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2280:Prentice Hall
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2255:
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2236:0-262-16209-1
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2190:3-540-08360-X
2186:
2182:
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2159:
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2141:
2137:
2130:
2116:on 2008-07-05
2115:
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2011:
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737:(struct foo))
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684:Ada2012 adds
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485:
477:
476:memory safety
467:
464:
458:
448:
446:
442:
438:
434:
426:
422:
418:
414:
400:
396:
393:
388:
384:
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376:wild pointers
373:
372:
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370:Memory safety
368:
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139:
137:
136:Substructural
134:
132:
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127:
124:
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119:
117:
114:
112:
109:
107:
104:
102:
99:
98:
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55:
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40:
38:
35:
34:
33:
32:
28:
27:
24:
21:
20:
2512:(2): 25–26.
2509:
2505:
2489:(1): 38–94.
2486:
2482:
2465:
2442:
2417:. Retrieved
2407:
2396:. Retrieved
2386:
2374:. Retrieved
2365:
2353:. Retrieved
2344:
2332:. Retrieved
2311:
2305:
2297:
2269:
2254:
2245:
2226:
2220:
2209:. Retrieved
2199:
2172:
2166:
2142:(4): 50–59.
2139:
2135:
2129:
2118:. Retrieved
2114:the original
2109:
2100:
2088:
2053:
2043:
2033:
2026:
1991:
1981:
1957:(1): 38–94.
1954:
1950:
1940:
1929:. Retrieved
1888:
1884:
1864:. Retrieved
1860:
1851:
1825:dynamic_cast
1817:
1549:
1538:
1417:
1414:C++ examples
1405:In general,
1404:
1390:
1374:
1368:
1237:
1131:
1054:
902:
871:
862:
858:
845:
843:
830:
824:
804:
793:
771:dynamic cast
746:
719:
705:, where the
695:
683:
668:
638:
621:
614:
609:
605:
595:
584:
568:
552:
522:into a dead
473:
460:
433:Type punning
424:
410:
395:Logic errors
345:
329:
323:
280:
270:
268:
259:Robin Milner
256:
247:polymorphism
236:
228:compile time
222:
193:
189:
183:
121:Intersection
36:
23:Type systems
2548:Type theory
2462:"Type Safe"
2093:Standard ML
1837:Type theory
1821:static_cast
1753:static_cast
1407:Common Lisp
1401:Common Lisp
873:Standard ML
868:Standard ML
846:type safety
660:pragma Pure
591:type system
417:Standard ML
253:Definitions
202:type errors
190:type safety
85:Duck typing
37:Type safety
2537:Categories
2431:References
2419:2022-09-21
2398:2022-09-21
2282:. p.
2211:2023-09-15
2120:2008-07-17
2009:0897910656
1931:2008-10-08
1866:2023-06-27
1819:replacing
833:inside an
664:Unchecked_
656:Unchecked_
624:reflection
306:expression
239:expression
131:Refinement
80:structural
2260:Kernighan
2144:CiteSeerX
2080:235474098
2037:(Thesis).
1973:0890-5401
1762:&>
1564:namespace
1489:&>
1432:namespace
1379:DualTypes
1361:DualTypes
1289:DualTypes
850:allocated
764:templates
617:interface
441:libraries
399:semantics
324:preserved
243:subtyping
210:data type
106:Dependent
2526:10426644
2477:(1994).
2440:(2002).
2355:24 March
2334:24 March
2018:11319320
1831:See also
1792:<<
1780:<<
1555:#include
1513:<<
1507:<<
1423:#include
1371:TwoTypes
1343:TwoTypes
1250:TwoTypes
1168:CARDINAL
1091:CARDINAL
1056:SYSTEM.
1032:(* or *)
1020:CARDINAL
1008:CARDINAL
899:Modula-2
811:generics
606:contract
526:of type
524:variable
437:run-time
425:believed
357:operator
301:Progress
232:run-time
101:Abstract
71:inferred
67:Manifest
1588:virtual
1304:Integer
1265:Integer
1192:INTEGER
1156:INTEGER
1115:INTEGER
1079:INTEGER
1041:INTEGER
996:INTEGER
954:ADDRESS
881:Mythryl
831:happens
548:pointer
421:Haskell
364:divisor
218:integer
146:Session
116:Gradual
76:Nominal
62:dynamic
2524:
2450:
2376:26 May
2290:
2233:
2187:
2146:
2078:
2068:
2016:
2006:
1971:
1804:return
1759:Child2
1741:Child2
1720:Parent
1693:Child1
1663:public
1657:Parent
1654:public
1648:Child2
1627:public
1621:Parent
1618:public
1612:Child1
1594:Parent
1582:public
1576:Parent
1525:return
1295:record
1256:record
1239:Pascal
1234:Pascal
1213:IMPORT
1210:UNSAFE
1180:UNSAFE
1141:UNSAFE
1138:IMPORT
1103:SYSTEM
1064:SYSTEM
1061:IMPORT
966:SYSTEM
948:SYSTEM
930:SYSTEM
912:SYSTEM
909:IMPORT
835:object
807:object
757:malloc
735:sizeof
729:void *
724:malloc
711:printf
709:tells
610:comply
463:Liskov
361:string
283:static
216:to an
214:string
206:values
141:Unique
126:Latent
58:Static
2522:S2CID
2076:S2CID
2014:S2CID
1843:Notes
1823:with
1744:&
1723:&
1669:float
1645:class
1609:class
1573:class
1561:using
1486:float
1471:float
1429:using
1377:with
885:MLton
839:class
604:as a
598:class
402:them.
310:value
271:sound
2448:ISBN
2378:2013
2357:2015
2336:2015
2288:ISBN
2231:ISBN
2185:ISBN
2066:ISBN
2004:ISBN
1969:ISSN
1795:endl
1777:cout
1756:<
1684:main
1516:endl
1510:fval
1504:cout
1495:ival
1483:<
1474:fval
1456:ival
1444:main
1316:Real
1277:Real
1247:type
1207:FROM
1186:CAST
1109:CAST
978:word
960:addr
942:addr
936:WORD
924:word
883:and
825:The
821:Java
751:The
696:The
669:The
575:Rust
423:are
334:and
285:and
245:and
192:and
78:vs.
69:vs.
60:vs.
2514:doi
2491:doi
2487:115
2284:116
2177:doi
2154:doi
2058:doi
1996:doi
1959:doi
1955:115
1903:hdl
1893:doi
1681:int
1633:int
1567:std
1453:int
1441:int
1435:std
1391:are
1373:is
1328:var
1322:end
1283:end
1216:FFI
1147:VAR
1070:VAR
987:VAR
972:ADR
921:VAR
753:new
743:C++
640:Ada
635:Ada
602:API
585:In
184:In
2539::
2520:.
2508:.
2485:.
2481:.
2464:.
2320:^
2296:.
2286:.
2278::
2262:;
2183:.
2152:.
2138:.
2108:.
2074:.
2064:.
2052:.
2012:.
2002:.
1990:.
1967:.
1953:.
1949:.
1916:^
1901:,
1889:17
1887:,
1875:^
1859:.
1783:c2
1771:);
1747:c2
1732:c1
1702:c1
1696:c1
1687:()
1678:};
1642:};
1606:};
1600:{}
1597:()
1498:);
1447:()
1355:D2
1349:D1
1337:T2
1331:T1
1201:);
1177::=
1124:);
1100::=
1050:);
1038::=
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1017::=
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963::=
841:.
817:.
802:.
795:C#
790:C#
707:%d
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596:A
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188:,
2528:.
2516::
2510:7
2499:.
2493::
2468:.
2456:.
2422:.
2401:.
2380:.
2359:.
2338:.
2239:.
2214:.
2193:.
2179::
2160:.
2156::
2140:9
2123:.
2082:.
2060::
2020:.
1998::
1975:.
1961::
1934:.
1905::
1895::
1869:.
1813:}
1810:;
1807:0
1798:;
1789:b
1786:.
1768:p
1765:(
1750:=
1735:;
1729:=
1726:p
1717:;
1714:5
1711:=
1708:a
1705:.
1699:;
1690:{
1675:;
1672:b
1666::
1660:{
1651::
1639:;
1636:a
1630::
1624:{
1615::
1591:~
1585::
1579:{
1570:;
1534:}
1531:;
1528:0
1519:;
1492:(
1477:=
1465:;
1462:5
1459:=
1450:{
1438:;
1364:;
1358::
1352:,
1346:;
1340::
1334:,
1325:;
1319:;
1313::
1310:Q
1307:;
1301::
1298:I
1292:=
1286:;
1280:;
1274::
1271:Q
1268:;
1262::
1259:I
1253:=
1219:;
1198:n
1195:,
1189:(
1183:.
1174:i
1171:;
1165::
1162:n
1159:;
1153::
1150:i
1144:;
1121:n
1118:,
1112:(
1106:.
1097:i
1094:;
1088::
1085:n
1082:;
1076::
1073:i
1067:;
1047:n
1044:(
1035:i
1026:i
1023:(
1014:n
1011:;
1005::
1002:n
999:;
993::
990:i
975:(
969:.
957:;
951:.
945::
939:;
933:.
927::
915:;
692:C
534:t
510:t
486:t
389:.
366:.
319:)
173:e
166:t
159:v
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