Satish R. Thatte. Quasi-static typing. In Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, San Francisco, CA, January 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....to both type checking polymorphic recursion [Myc84, Hen88] and (strong) subsumption [DR90] on feature trees. We extend this correlation by showing how weak subsumption relates to soft typing. In recent years, there has been increasing interest in type analysis for untyped languages (soft typing) [Tha90, AW93, AWL94, CF91, WC94]. By far most of the typing literature is for functional languages. The close relationship between constraint solving and type inference ( Wan87, AW93, PS94] and many others) or more general program analysis (e.g. Hei92, PS94] is well established. Among the abounding literature, the work of ....

S. R. Thatte. Quasi-static Typing. In 7 ACM Symposium on Principles of Programming Languages, pp. 367--381. CACM, January 1990.

....considered languages with dynamic types. Some of these studies deal with the automatic insertion of dynamic creations and coercions that turn ambivalent programs (programs that cannot be recognized type safe nor type erroneous at compile time) into equivalent programs with run time type checks [24, 12]. One motivation is to integrate more transparently dynamically typed and statically typed objects; another motivation is the ecient compilation of programs written in dynamically typed languages such as Scheme. In our proposal, we insist on keeping the coercions to and from dynamics explicit in ....

Satish R. Thatte. Quasi-static typing. In 17th symposium Principles of Programming Languages, pages 367-381. ACM Press, 1990. 31

....we can use more powerful type languages without restricting the set of accepted programs due to inaccuracies of the type checker and without enforcing explicit type annotations. e.g. subtyping as a step towards powerful type languages as found in e.g. 1] 8] or partial types as presented in [9, 10] can be processed by our type checker. Our type checker is described as an abstract interpretation and yields detailed support in detecting type errors. Furthermore, warnings of an additional sound soft typing system [2] 16] or a system with output similar to soft typing [4] can be used ....

S. R. Thatte. Quasi-static typing. In Conference Record of the Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 367-381, San Francisco, California, Jan. 1990.

....go, but none of the other bugs, because the accesses in question did not stray far enough to be noticed. 10 Related Work Abadi et al. 1] study the theoretical aspects of adding a Dynamic type to the simply typed calculus and discuss extensions to polymorphism and abstract data types. Thatte [28] extends their system to replace the typecase expressions with implicit casts. Their system does not handle reference types or memory updates and Dynamic types are introduced to add exibility to the language. In contrast our system was designed to handle memory reads and writes, allows DYNAMIC ....

S. Thatte. Quasi-static typing. In Conference record of the 17th ACM Symposium on Principles of Programming Languages (POPL), pages 367-381, 1990.

....of subsumption. Example 6 ffl The system Sigma 1 , where Sigma 1 = Tv [ f ; natg, is the system of recursive types studied by Amadio and Cardelli [3] ffl The system Sigma 2 , where Sigma 2 = Tv[f ; natg, is sometimes called the system of partial types, after the work of Thatte [32, 33, 34], who studied a nonrecursive version. Other well known calculi with but not include F : 6] and O 1 [1] ffl The system Sigma 3 , where Sigma 3 = Tv [ f ; natg may be viewed as a dual of Sigma 2 . ffl The system Sigma 0 , where Sigma 0 = Tv [ f ; natg, is the system of recursive ....

Satish R. Thatte. Quasi-static typing. In Conference Record of the Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 367-- 381, 1990.

....based, in turn, on earlier works of Thatte and Gomard [Gom90] Thatte originally worked with a system called partial types [Tha88] in which types could be coerced to a universal type, but not vice versa a pure subtyping system. Coercions from type Dynamic were introduced in a subsequent paper [Tha90]; as discussed in Section 3, this is not subtyping. A large number of analysis algorithms for dynamically typed languages have been proposed in recent years [Gom90, AM91, CF91, Hen92b, WH92, WC94] With the exception of the works of Henglein, Thatte, and Gomard, it is fair to characterize all of ....

S. Thatte. Quasi-static typing. In Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 367--381, January 1990.

....of reference, amongst other things. 7 Related work The dynamic calculus of Section 3 is reminiscent of a subtyping discipline, but it is critically different in that both tagging and untagging coercions are present. In this regard it is closely related to Thatte s notion of quasi static typing [Tha90] where tagging and untagging are referred to as positive and negative coercions, respectively. A subtyping discipline has only positive coercions. In Thatte s language, however, the types of bound variables must be explicitly declared and it is thus not suitable for application in automatic ....

S. Thatte. Quasi-static typing. In Proc. ACM Symp. on Principles of Programming Languages, pages 367--381, ACM, Jan. 1990.

....for snk(ff) 4. If both src(ff) and snk(ff) contain at least two types with distinct type constructors each, this signals that values of different types can reach the expression(s) e with low type ff and that e may be used in operations requiring different types. This is a plausible situation [Tha90], as all the operations may work without type error at run time. In this case the type tagging and checking will have to be done at run time: we unify ff with ( Dynamic where all the nonvariable types of src(ff) and snk(ff) enter as summands. Since snk(ff) should give all the possible ....

S. Thatte. Quasi-static typing. In Proc. ACM Symp. on Principles of Programming Languages, pages 367--381. ACM, Jan. 1990.

....language which is expressible in an untyped language (such as Lisp or Scheme) if a program in the latter language cannot be statically type checked in certain places, then insert run time checks into the code. This approach is exemplified by approaches such as partial types (Thatte 1989; Thatte 1990) and soft typing (Cartwright and Fagan 1991; Aiken, Wimmers, and Lakshman 1994; Wright and Cartwright 1994) However Thatte (1990) points out: Cardelli [personal communication] points out that automatic generation of run time checks could be dangerous since users might not be aware of the points ....

....statically type checked in certain places, then insert run time checks into the code. This approach is exemplified by approaches such as partial types (Thatte 1989; Thatte 1990) and soft typing (Cartwright and Fagan 1991; Aiken, Wimmers, and Lakshman 1994; Wright and Cartwright 1994) However Thatte (1990) points out: Cardelli [personal communication] points out that automatic generation of run time checks could be dangerous since users might not be aware of the points where they are being used. A slight change to a statically well typed program may unwittingly cause a whole set of automatic ....

Thatte, S. (1990, January). Quasi-static typing. In Proceedings of ACM Symposium on Principles of Programming Languages, pp. 367--381. ACM Press.

....of subsumption. Example 6 ffl The system Sigma 1 , where Sigma 1 = Tv [ f ; natg, is the system of recursive types studied by Amadio and Cardelli [3] ffl The system Sigma 2 , where Sigma 2 = Tv[f ; natg, is sometimes called the system of partial types, after the work of Thatte [33, 34, 35], who studied a nonrecursive version. Other well known calculi with but not include F : 6] and O 1 [1] ffl The system Sigma 3 , where Sigma 3 = Tv [ f ; natg, was studied by Cardone and Coppo [7, 8] Although Cardone and Coppo claim that type inference for this system is solved, we ....

Satish R. Thatte. Quasi-static typing. In Conference Record of the Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 367-- 381, 1990.

....the pattern. This sort of matching does not work out well with more general typecase patterns. We find it preferable to match type tags against patterns exactly, and then perform explicitly prescribed subtype tests. In addition to [1] several recent studies consider languages with dynamic types [12, 14, 21]. The work most relevant to ours is that of Leroy and Mauny, who define and investigate two extensions of ML with dynamic types. We compare their designs to ours in section 4. Section 2 is a brief review of dynamic typing in simply typed languages, based on [1] Section 3 considers the addition of ....

Satish R. Thatte. Quasi-static typing (preliminary report). In Proceedings of the Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, 1990.

....(assignment and control) and implemented efficiently, it could serve as the basis for a stronger soft type system for Scheme. Several researchers have developed static type systems that extend the Hindley Milner type discipline by adding a maximal type as the type of otherwise untypable phrases [7, 8, 16, 20, 21]. This framework is too imprecise to form the basis for a soft type system because it does not support union types or inferred recursive types. The frequency with which is assigned as the type of a phrase prevents its use as a reliable indicator of potential program errors. Nevertheless, ....

Thatte, S. R. Quasi-static typing. Proceedings of the 17th Annual Symposium on Principles of Programming Languages (January 1990), 367--381.

....dynamic forms of data. It does not meet the criteria for soft typing because the programmer must annotate his program with explicit tagging operations to create dynamic values. In addition, programs are still rejected; narrowers are not inserted by the type checker. More recently, Thatte[20] has developed the notion of quasi static typing that augments a static type system with a general type Omega Gamma Thatte s system resembles soft typing in that it insert narrowers when necessary, ensuring that all programs can be executed. However, it does not meet the other criteria required ....

Sattish Thatte. Quasi-static typing. In Proceedings of the Seventeenth POPL Symposium, 1990.

....f( u) f( v) u v [ u 1 0 : un 0 ] This deviates from their formal semantics. For illustration, observe that f(a; 0) f(b; 0) holds but a b 0 0 does not. Interestingly, however, this optimization is formally justified over P (T Sigma ) 3 Type Inference. Thatte s partial types [41] are finite trees over the the binary constructor and the constant Omega ; the subtyping order treats contravariant and has Omega as greatest element (no covariant constructors) Kozen et al. have given a constraint based algorithm for inference of partial types [28] which has cubic ....

S. Thatte. Quasi-static typing. In Conference Record of the 7th Annual ACM Symposium on Principles of Programming Languages, San Francisco, CA, pages 367--381, 11 West 42nd Street, New York, N.Y 10036, January 1990. ACM, ACM.

....Again, this work could be incorporated into our sort inference algorithm, and would provide even greater 8.3 Further Work 183 information about the sort of an action. Finally, there are related problems in type inference. Recent work has focussed on type inference for dynamically typed languages [AM91,Tha91,CF91,Hen92,AW93, HR95]. Henglein and Rehof[Hen92, HR95] have addressed the problem of inserting dynamic type checks in SCHEME programs. Significantly, they have identified the minimum number of checks that must be inserted to guarantee the program will run without a type error. Currently the action notation sort ....

S. R. Thatte. Quasi-static typing. In Conference Record of the 17th Annual ACM Symposium on Principles of Programming Languages, pages 367--381, 1991.

....based, in turn, on earlier works of Thatte and Gomard [Gom90] Thatte originally worked with a system called partial types [Tha88] in which types could be coerced to a universal type, but not vice versa a pure subtyping system. Coercions from type Dynamic were introduced in a subsequent paper [Tha90]. A large number of analysis algorithms for dynamically typed languages have been proposed in recent years [Gom90, AM91, CF91, Hen92b, WH92, WC94] With the exception of the works of Henglein, Thatte, and Gomard, it is fair to characterize all of these as (inclusion based) subtyping systems; none ....

S. Thatte. Quasi-static typing. In Seventeenth Annual ACM Symposium on Principles of Programming Languages, pages 367--381, January 1990.

....[29] by Leroy [30] by Poulsen [41] by Henglein and J rgensen [24] and by Shao [43] with the goal of minimizing the overhead of boxing and unboxing at run time. All but the first of these approaches involve copying coercions. Of a broadly similar nature is the work on soft type systems [3, 10, 23, 49, 53] that seek to improve data representations through global analysis techniques. All of these methods are based on the use of program analysis techniques to reduce the overhead of box and tag manipulation incurred by the standard compilation method for polymorphic languages. Many (including the soft ....

S. R. Thatte. Quasi-static typing. In Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, San Francisco, CA, Jan. 1990.

....He does not use control analysis but seems to eliminate more tests than our analysis do: the author claims to remove from 60 to 95 of the tests. His analysis is entirely devoted to type checking, not to closure allocation improvement. ffl Cartwright, Wright and Fagan in [2, 21] and Thatte in [19] show systems performing partial static type 4 Kranz is a bit more precise since closures requiring environment allocation are themself divided into two parts, the ones which are heap allocated and the ones which are stack allocated. Our compiler also performs stack allocations but since this ....

S. Thatte. Quasi-static Typing. In Proceedings of the ACM Symposium of Principles of Programming Languages, pages 367--381, 1990.

....boxing interpretation of polymorphism has been studied by Peyton Jones Launchbury [30] by Leroy [32] by Poulsen [43] and by Henglein J rgensen [24] with the goal of minimizing the overhead of boxing and unboxing at run time. Of a broadly similar nature is the work on soft type systems [3, 11, 23, 48, 53] which seek to improve data representations through global analysis techniques. All of these methods are based on the use of program analysis techniques to reduce the overhead of box and tag manipulation incurred by the standard compilation method for polymorphic languages. Many (including the ....

Satish R. Thatte. Quasi-static typing. In Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, San Francisco, CA, January 1990.

....languages with implicit polymorphism in the ML style. The same ideas can be used, with some interesting twists. In particular, we are led to introduce tuple variables, which stand for tuples of type variables. In addition to [1] several recent studies have considered languages with dynamic types [14, 17, 23]. The work most relevant to ours is that of Leroy and Mauny, who define and investigate two extensions of ML with dynamic types. We compare their designs to ours in section 6. Section 2 is a brief review of dynamic typing in simply typed languages, based on [1] Section 3 considers the general ....

Satish R. Thatte. Quasi-static typing (preliminary report). In Proceedings of the Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, 1990.

No context found.

Satish R. Thatte. Quasi-static typing. In Seventeenth ACM Symposium on Principles of Programming Languages, pages 367--381, San Francisco, CA, January 1990.

No context found.

S. Thatte. Quasi-static typing. In Conference record of the 17th ACM Symposium on Principles of Programming Languages (POPL), pages 367--381, 1990.

No context found.

S. Thatte. Quasi-static typing. In Conference record of the 17th ACM Symposium on Principles of Programming Languages (POPL), pages 367--381, 1990.

No context found.

S. Thatte. Quasi-static typing. In Conference record of the 17th ACM Symposium on Principles of Programming Languages (POPL), pages 367--381, 1990.

No context found.

Thatte, Satish R. "Quasi-static Typing". 17'th ACM POPL '90, Jan. 1990,367-381.

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