P. Wadler. The marriage of effects and monads. In International Conference on Functional Programming (ICFP), volume 34(1) of SIGPLAN Notices, pages 63--74, 1998.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....I O Or I O but not concurrency The answer is technically, yes of course. There is a long history of research into so called effect systems, that track what kind of effects an expression can have [21] Such effect systems can be expressed in a monadic way, or married with a monadic type system [51]. However, the overhead on the programmer becomes greater, and I do not know of any language that uses such a system . An interesting challenge remains, to devise a more refined system that is still practical; there is some promising work in this direction [6, 51, 45, 5] Meanwhile I argue that ....

....married with a monadic type system [51] However, the overhead on the programmer becomes greater, and I do not know of any language that uses such a system . An interesting challenge remains, to devise a more refined system that is still practical; there is some promising work in this direction [6, 51, 45, 5]. Meanwhile I argue that a simple pure or impure distinction offers an excellent cost benefit tradeoff. 8 Summary We have surveyed Haskell s monadic I O system, along with three significant language extensions . It is easy to extend a language, though Are these extensions any good Are they ....

WADLER, P. The marriage of effects and monads. In ICFP98 [18], pp. 63--74.

....and deallocations follow a stack discipline in unison with the original program s expression structure. The original inspiration for Tofte and Talpin s region calculus came from work on effect systems [4, 12] Recent research shows how such systems can be represented in the monadic lambda calculus [17, 10]. The TT system is efficient for smaller programs [15] but requires a number of extra analyses to give reasonable behavior for larger programs [2] The problem is that in practice object lifetimes do not follow a stack discipline. In the ML Kit [13] a compiler for Standard ML using region based ....

P. Wadler. The marriage of effects and monads. In International Conference on Functional Programming (ICFP), volume 34(1) of SIGPLAN Notices, pages 63--74, 1998.

....[93] to introduce side effects in a functional manner. In this system, the type of every impure function is enriched with information about which variables are read or written when it is executed. This approach is as an alternative to monads. In some instances the two are indeed equivalent [54, 98]. Effects were later used to develop region based memory management [11, 95] In this approach, each type carries the name of a region where it is allocated, in addition to the standard effect information. This 4 For the reader familiar with subtyping, the distinction alluded to here is related ....

Philip Wadler. The marriage of effects and monads. In the International Conference on Functional Programming (ICFP '98), volume 34(1) of ACM SIGPLAN Notices, pages 63--74. ACM, June 1999.

....the advantages of pure functional programming with the flexibility of imperative (or other styles of) programming. The analogies of computational types with effect systems [GL86] have been observed by [Wad92] but formal relations between the two have been established only recently (e.g. see [Wad98] In the denotational semantics of programming languages there are other informal notions modeled using monads, for instance collection types in database languages [BNTW95] or collection classes in object oriented languages [Man98] It is important to distinguish the mathematical notion of ....

....This section describes how type and effect analyses can be presented in terms of monads and the computational metalanguage. Although this is actually rather obvious, it was only recently that anybody got around to writing anything serious about it. In ICFP 1998, Wadler published a paper [Wad98] later extended and corrected as [WT99] showing the equivalence of a mild variant of the effect system of Talpin and Jouvelot [TJ94] and a version of the computational metalanguage in which the computation type constructor is indexed by effects. In the same conference, Benton, Kennedy and ....

P. Wadler. The marriage of effects and monads. In International Conference on Functional Programming. ACM Press, 1998.

....Since the semantics of ML like languages is easily expressed via a translation to monadic style, it should be possible to reason about memory encapsulation of ML programs by translating to monadic style and using monadic encapsulation. Indeed, Wadler recently explored part of this idea [Wad98] He shows that effect systems (without masking) can be translated to a monadic framework (without encapsulation) but with additional annotations for effects and regions. In contrast, we relate a restricted effect system (with masking) to the standard monadic framework of Launchbury and Peyton ....

....encapsulate references within arbitrary program expressions. The type system for this language uses a simplified form of effect inference and effect masking. We define the semantics using a translation to a monadic language in which encapsulation is enforced by runST. Building on Wadler s result [Wad98] we give a transformation from the first language to the second which preserves typability. This confirms a folklore statement that the traditional monadic framework implements a cheap form of region inference and effect masking. We then revisit the problem of monadic encapsulation and show that ....

[Article contains additional citation context not shown here]

Philip Wadler. The marriage of effects and monads. In International Conference on Functional Programming, pages 63--74, Baltimore, September 1998. ACM.

....the advantages of pure functional programming with the flexibility of imperative (or other styles of) programming. 4 The analogies of computational types with effect systems [GL86] have been observed by [Wad92] but formal relations between the two have been established only recently (e.g. see [Wad98] In the denotation semantics of programming languages there are other informal notions modeled using monads, for instance collection types in database languages [BNTW95] or collection classes in object oriented languages [Man98] It is important to distinguish the mathematical notion of monad ....

....This section describes how type and effect analyses can be presented in terms of monads and the computational metalanguage. Although this is actually rather obvious, it was only recently that anybody got around to writing anything serious about it. In ICFP 1998, Wadler published a paper [Wad98] showing the equivalence of a mild variant of the effect system of Talpin and Jouvelot [TJ94] and a version of the computational metalanguage in which the computation type constructor is indexed by effects. In the same conference, Benton, Kennedy and Russell described the MLj compiler [BKR98] and ....

P. Wadler. The marriage of effects and monads. In International Conference on Functional Programming. ACM Press, 1998.

....Lifting allows us to model callby value calculi. Second, instead of having one type constructor T semantically associated with a monad, the calculus incorporates multiple type constructors T , one for every element 2 L of a predetermined lattice L . This idea was also considered by Wadler [39]. The lattice represents different grades of information. In the security setting, the least element usually stands for low security. Type constructors T change the level of a type. For instance T H (bool) describes high security booleans. Third, the monad bind operation has a special typing ....

P. Wadler. The marriage of effects and monads. In Proceedings of the 1998 ACM SIGPLAN International Conference on Functional Programming, pages 63--74. ACM, 1998.

....in ML. Since the semantics of ML like languages is easily expressed via a translation to monadic style, it should be possible to reason about memory encapsulation of ML programs by translating to monadic style and using monadic encapsulation. Indeed, Wadler recently explored part of this idea [Wad98] He shows that effect systems (without masking) can be translated to a monadic framework (without encapsulation) but with additional annotations for effects and regions. In contrast, we relate a restricted effect system (with masking) to the standard monadic framework of Launchbury and Peyton ....

....encapsulate references within arbitrary program expressions. The type system for this language uses a simplified form of effect inference and effect masking. We define the semantics using a translation to a monadic language in which encapsulation in enforced by runST. Building on Wadler s result [Wad98] we give a transformation from the first language to the second which preserves typability. This confirms a folklore statement that the traditional monadic framework implements a cheap form of region inference and effect masking. We then revisit the problem of monadic encapsulation and show ....

Philip Wadler. The marriage of effects and monads. In International Conference on Functional Programming, pages 63--74, Baltimore, September 1998. ACM.

....(and kept up to date) by subsequent optimizations, rather than in an auxiliary data structure. An advantage of the monadic semantics is that it provides a natural foundation for probing and proving the correctness of transformations in the presence of a variety of effects. In related work, Wadler [20] has recently and independently shown that Talpin and Jouvelot s effect inference system can be applied in a monadic framework; he uses an untyped semantics, and considers only store effects. In another independent project, Benton and Kennedy are prototyping an ML compiler with an IR that ....

P. Wadler. The marriage of effects and monads. (unpublished manuscript), Mar. 1998.

.... do not present the semantics in terms of monads, the idea to use both resources and effects to describe a function s interoperability was inspired by recent work on monad based interactions and modular interpreters [21, 9, 20, 10] and Wadler s work on the relationship between monads and effects [22]. Monads, viewed as compositions of basic monad transformers [10] can be used to represent sets of resources. The transition rules creating a binding activation frame and binding a variable to a value (Figure 12) given a set of resources, provide the semantics of the bind and unit of the ....

Philip Wadler. The marriage of effects and monads. In ACM SIGPLAN International Conference on Functional Programming, pages 63--74. ACM Press, 1998.

....of polymorphic equality. They also help catch compiler bugs In our case it seems especially natural, as the Java bytecode which we eventually produce is itself typed. The use of computational types in the intermediate language is more unusual, though similar systems have recently been proposed in [23, 11, 24] and the use of a monadic intermediate language to express strictness based optimisations was proposed in [4] The separation of computations and values gives MIL a pleasant equational theory (full fi and j rules plus commuting conversions) which makes correct rewriting simpler. Order of ....

P. Wadler. The marriage of effects and monads. In 3rd ACM SIGPLAN Conference on Functional Programming, September 1998. (this volume).

....[SW97] Our reduction semantics for the monad is new. It most closely resembles the work of Hatcliff and Danvy, but they did not deal with state and therefore failed to distinguish between pure reductions and those with computational effects, as we do here. This paper is a revised version of [Wad98] Changes include the use of type schemes (rather than following Talpin and Jouvelot in the use of substitution) the use of an optimized monad translation (which greatly simplifies the proof that the translation preserves the semantics) the introduction of evaluation contexts in the operational ....

P. Wadler, The marriage of effects and monads, ACM 3'rd International Conference on Functional Programming, Baltimore, September 1998.

No context found.

P. Wadler. The marriage of effects and monads. In International Conference on Functional Programming (ICFP), volume 34(1) of SIGPLAN Notices, pages 63--74, 1998.

No context found.

Comput., 132(2), 109--176. Wadler, Philip. (1998). The marriage of effects and monads. Pages 63--74 of: the ACM SIGPLAN International Conference on Functional Programming. ACM Press, New York.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC