Leif Andersen
Bio
Leif Andersen is a PhD student studying programming languages in Northeastern University’s College of Computer and Information Science, advised by Professor Matthias Felleisen. She is a part of the Programming Research Laboratory (PRL) and studies topics in Programming Languages and Human Computer Interaction. Specifically, she works on domain-specific languages for creating hybrid textual-visual programs.Papers
- Adding Interactive Visual Syntax to Textual CodeAuthors: Leif Andersen, Michael Ballantyne, Matthias FelleisenAbstract:
Many programming problems call for turning geometrical thoughts into code: tables, hierarchical structures, nests of objects, trees, forests, graphs, and so on. Linear text does not do justice to such thoughts. But, it has been the dominant programming medium for the past and will remain so for the foreseeable future. This paper proposes a novel mechanism for conveniently extending textual programming languages with problem-specific visual syntax. It argues the necessity of this language feature, demonstrates the feasibility with a robust prototype, and sketches a design plan for adapting the idea to other languages.
View... - Super 8 Languages for Making MoviesAuthors: Leif Andersen, Stephen Chang, Matthias FelleisenAbstract:
The Racket doctrine tells developers to create languages (as libraries) to narrow the gap between the terminology of a problem domain and general programming constructs. This pearl illustrates this doctrine with the creation of a relatively simple domain-specific language for editing videos. To produce the video proceedings of a conference, for example, video professionals traditionally use ``non-linear'' GUI editors to manually edit each talk, despite the repetitive nature of the process. As it turns out, the task of video editing naturally splits into a declarative phase and an imperative rendering phase at the end. Hence it is natural to create a functional-declarative language for the first phase, which reduces a lot of manual labor. The implementation of this user-facing DSL, dubbed Video, utilizes a second, internal DSL to implement the second phase, which is an interface to a general, low-level C library. Finally, we inject type checking into our Video language via another DSL that supports programming in the language of type formalisms. In short, the development of the video editing language cleanly demonstrates how the Racket doctrine naturally leads to the creation of language hierarchies, analogous to the hierarchies of modules found in conventional functional languages.
View... - Feature-Specific ProfilingAuthors: Leif Andersen, Vincent St-Amour, Jan Vitek, Matthias FelleisenAbstract:
While high-level languages come with significant readability and maintainability benefits, their performance remains difficult to predict. For example, programmers may unknowingly use language features inappropriately, which cause their programs to run slower than expected. To address this issue, we introduce feature-specific profiling, a technique that reports performance costs in terms of linguistic constructs. Festure-specific profilers help programmers find expensive uses of specific features of their language. We describe the architecture of a profiler that implements our approach, explain prototypes of the profiler for two languages with different characteristics and implementation strategies, and provide empirical evidence for the approach's general usefulness as a performance debugging tool.
View... - Feature-Specific ProfilingAuthors: Vincent St-Amour, Leif Andersen, Matthias FelleisenAbstract:
High-level languages come with significant readability and maintainability benefits. Their performance costs, however, are usually not predictable, at least not easily. Programmers may accidentally use high-level features in ways that compiler writers could not anticipate, and they may thus produce underperforming programs as a result. This paper introduces feature-specific profiling, a profiling technique that reports performance costs in terms of linguistic constructs. With a feature-specific profiler, a programmer can identify specific instances of language features that are responsible for performance problems. After explaining the architecture of our feature-specific profiler, the paper presents the evidence in support of adding feature-specific profiling to the programmer’s toolset.
View... - Concrete and Abstract Interpretation: Better TogetherAuthors: Maria Jenkins, Leif Andersen, Thomas Gilray, Matthew MightAbstract:
Recent work in abstracting abstract machines provides a methodology for deriving sound static analyzers from a concrete semantics by way of abstract interpretation. Consequently, the concrete and abstract semantics are closely related by design. We apply Galois-unions as a framework for combining both concrete and abstract semantics, and explore the benefits of being able to express both in a single semantics. We present a methodology for creating such a unified representation using operational semantics and implement our approach with and A-normal form (ANF) λ-calculus for a CESK style machine in PLT Redex.
View... - Multi-core Parallelization of Abstract Abstract MachinesAuthors: Leif Andersen, Matthew MightAbstract:
It is straightforward to derive well-known higher-order flow analyses as abstract interpretations of well-known abstract machines. In this paper, we explore multi-core parallel evaluation of one such abstract abstract machine, the CES machine. The CES machine is a variant of CESK machines that runs Continuation Passing Style (CPS) λ-calculus. Using k-CFA, the concrete semantics for a CES machine can be turned into abstract semantics. Analyzing a program for this machine is a state graph walk, which can be run in parallel to increase performance.
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