StackEffekt

StackEffekt is a theoretical framework in programming language design that describes how to model and manage computational effects by maintaining a stack of effect contexts during program execution. The approach emphasizes modular control over side effects, such as input/output, state, exceptions, and concurrency, by making them explicit and composable within a stack structure.

Origin and terminology: The name StackEffekt blends the concept of a runtime stack with Effekt, the German word for effect, and is used in academic discussions of effect systems to illustrate stack-based handling of effects.

Core idea: In StackEffekt, every expression interacts with an effect stack. Entering a scope that introduces an effect pushes a corresponding context onto the stack; leaving the scope or handling the effect pops the context and resumes computation.

Semantics: Operations that request an effect, often labeled perform or op, push the effect onto the stack; handlers intercept and resolve effects, potentially transforming results or resuming computation.

Type system: The effect stack integrates with the type system through effect rows or polymorphic labels; type inference accounts for required and available handlers to ensure well-typed compositions.

Relation to other approaches: StackEffekt is related to algebraic effects and effect handlers and shares goals with delimited continuations and traditional effect systems; it emphasizes modular composition of effects via an explicit runtime stack rather than monadic layering.

Applications: Proposed uses include modular error handling, logging, tracing, resource management, and testing; the explicit stack supports static reasoning about where effects originate and how they are handled.

Status and criticism: As a theoretical construct, StackEffekt remains primarily in academic discourse; practical adoption requires language support for effect stacks, handlers, and inference, as well as integration with existing runtimes.

See also: Algebraic effects; Effect system; Effect handler; Delimited continuations.