M. Odersky. Observers for linear types. In Proceedings of 4th European Symposium on Programming (ESOP'92), Springer LNCS 582, pages 390--407, 1992.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....by inspection or logical reasoning. More interestingly, we would like to guarantee it by some static type system. We already know that linear typing, i.e. the absence of contraction, provides such a guarantee; we conjecture that the more general read only type systems and analyses described in [2, 12, 15, 18] all are able to provide such a guarantee as well, by suitably restricting but not altogether excluding the contraction rule. The important point here is that the semantic formalisation of benign sharing makes no reference to resource annotations so that discharging the extra assumption made is ....

Martin Odersky. Observers for linear types. In B. Krieg-Bruckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, pages 390-407. Springer-Verlag, February 1992. Lecture Notes in Computer Science 582.

....type to nonlinear form for the scope of the expression e1 , then returns it to its linear type for the scope of expression e2 . Wadler used a syntactic restriction on the type of e1 to prevent the escape of nonlinear references[17] Odersky later proposed observer types to prevent this escape [9]. Could we give our cell the linear type ref#int[ and then use Wadler s let to obtain a reference of nonlinear type to the cell Unfortunately, there are two issues that make let unsuitable in this case. First, while let is sound in its original setting of a functional language, it ....

....of a full copy [12] Linear type systems enable resource management at the granularity of a single object. Every use of an object of linear type consumes the object, leading to a programming style where linear objects are threaded through the computation. Wadler s let construct, or its variations [9], can be used to give a temporary nonlinear type to a object of linear type. Walker and Watkins [19] study a type system with three kinds of objects: linear, reference counted, and region allocated. The kind of an object is fixed at allocation without a means to change kind. They provide let only ....

M. Odersky. Observers for linear types. In B. Krieg-Bruckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, pages 390--407, New York, 1992. Springer-Verlag.

....under investigation, studies the modeling of impure effects. This will provide the easiness brought by impure effects to the programmer without losing the reference transparency of the model. The backbone of this work will be the study of the linear type system (see [Gir87] Laf88] Ode91] [Ode92], Wad90] and [Wad91] and the monad programming paradigm (see [Wad92a] and [Wad92b] A new semantic description of behaviors based on constraint equations and effect systems using algebraic reconstruction algorithms (see [LG88] and [JG88] will reduce the need for user intervention in the late ....

M. Odersky. Observers for linear types. Technical report, Yale Univ., February 1992.

.... 4 their type system does not have ffi type of values that must be used up locally, and instead it relies on a separate analysis for analyzing the order of memory access (so, the analysis is not integrated as a use type system, and it is rather complex) Guzm an and Hudak [7] and Odersky [17] also proposed a kind of an extension of a linear type system, which can take an evaluation order into account and check that destructive operations on arrays or lists are safely used. Unlike ours, their approach is to let programmers explicitly declare where destructive operations should be ....

Martin Odersky. Observers for linear types. In Proceedings of 4th European Symposium on Programming (ESOP'92), volume 582 of Lecture Notes in Computer Science, pages 390--407. Springer-Verlag, 1992.

....the uniqueness typing, as far as we can see from the description in the recent language report (p.62 of [18] of Concurrent Clean, it seems to assign real , real 2 1 real , and int ; int respectively to the arguments of (call by value versions of) add, swap, and twice. Odersky [17] also proposed an extension of a linear type system that allows a linear value to be used many times for non destructive operations before being used for destructive operations. Unlike ours, destructive operations are assumed to be explicitly specified by a programmer, not inferred automatically. ....

Martin Odersky. Observers for linear types. In Proceedings of 4th European Symposium on Programming (ESOP'92), volume 582 of Lecture Notes in Computer Science, pages 390--407. Springer-Verlag, 1992.

....become more expensive, more complex, more difficult to report and harder for the programmer to understand. 4 The alternative: prevention of implicit copying Recently two alternatives to using compile time analyses to optimise implicit copying in programs have been suggested: linear type systems [8, 13, 16, 18] and linear abstract data types [15] Both these approaches enforce linear manipulation of arrays; thereby guaranteeing that arrays are never shared. This allows replace operations to always be implemented by destructive updates. To copy a value (they cannot be shared) an explicit copy operation ....

....is a natural restriction that although linear types may reference shared types, shared types may not reference linear types. This ensures linear types are not shared indirectly via shared types. Wadler s system has been implemented by Wakeling [18] Two more sophisticated systems are proposed in [8, 13]. 4.2 Monads and linear ADTs In [15] Wadler has proposed using monads to structure functional programs. Monads can also be used to achieve linearity; that is to support the linear manipulation of arrays. This guarantees that arrays are unshared. These monad operations may be encapsulated into an ....

M Odersky. Observers for linear types. In European Symposium on Programming, February 1992.

.... Some examples of storage management optimizations are compile time garbage collection [15, 24] the aggregate update problem (determining when a functional operation on structured data can be done destructively) 3, 11, 20] verification of single threadedness in languages based on linear logic [21, 26], and determining when local variables may be replaced by global ones [25] Examples of other uses of storage analyses are interference and dependence analysis for automatic parallelization [2, 23] and improving code generation for instruction level parallelism [22, 27] Deutsch s alias analysis ....

Martin Odersky. Observers for linear types. In ESOP'92, volume 582 of Lecture Notes in Computer Science, pages 390--407. Springer Verlag, February 1992.

....This requirement is similar to that for linear types, but even stronger in that a linear entity can be freely destroyed by its current owner, i.e. a linear entity is always fully owned by the variable currently holding the reference to it. Borrow types are related to the concept of observer types[18], again from the domain of functional languages. However, just as for the linear types, there is little known about the integration into imperative settings 15 . A thorough investigation of these matters is underway as part of the ongoing Gardens Project. The novel concept of modal types ....

M. Odersky. Observers for linear types. In Proceedings of the European Symposium on Programming, February 1992.

....simply an efficient implementation technique. More recently, refinements of functional programming languages have emerged which re introduce mutable state without re introducing references as an observable concept. Programming languages based on linear type disciplines [Gir87, Wad90b, LM92, Bak92, Ode92, AP94, MOTW95, CH97] allow state to be updated destructively as long as it can be verified that only one reference to the state exists. In this case, updating state is indistinguishable from creating and modifying a copy. Programming languages based on monads [Mog89, Wad90a, Mog91, Wad92, HPW92] ....

Martin Odersky. Observers for linear types. In B. Krieg-Bruckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, pages 390--407. Springer-Verlag, February 1992. Lecture Notes in Computer Science 582.

....would hold only for the particular type system used. This would result in a loss in generality, since there are many possible candidates for such a type system. In particular, there are several widely differing approaches to implementing the effect checking required by the pure rule (examples are [8, 13, 18, 19, 21]) By keeping var untyped we avoid being overly specific. Also left to future research is the investigation of variants of var . A call by value variant promises to be a useful tool for reasoning about programs in existing imperative or impurely functional languages. A variant with ....

M. Odersky. Observers for linear types. In B. KriegBr uckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, Lecture Notes in Computer Science 582, pages 390--407. Springer-Verlag, February 1992.

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M. Odersky. Observers for linear types. In Proceedings of 4th European Symposium on Programming (ESOP'92), Springer LNCS 582, pages 390--407, 1992.

No context found.

Martin Odersky. Observers for linear types. In B. Krieg-Bruckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, pages 390--407. Springer-Verlag, February 1992. Lecture Notes in Computer Science 582.

No context found.

M. Odersky. Observers for linear types. In B. Krieg-Bruckner, editor, ESOP '92: 4th European Symposium on Programming, Rennes, France, Proceedings, pages 390--407. Springer-Verlag, February 1992. Lecture Notes in Computer Science 582.

No context found.

Odersky, M. Observers for linear types. In ESOP'92, Lecture Notes In Computer Science, volume 582, pages 390-407. Springer Verlag, February 1992.

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