Abstract Jane Street Capital is a successful proprietary trading company that uses OCaml as its primary development language. We have over twenty OCaml programmers and hundreds of thousands of lines of OCaml code. We use OCaml for a wide range of tasks: critical trading systems, quantitative research, systems software, and system administration. We value OCaml because it allows us to rapidly produce readable, correct, efficient code to solve complex problems, and to change that code quickly to adapt to a changing world. We believe that using OCaml gives us a significant advantage over competitors that use languages like VB, Perl, C++, C#, or Java. It also makes finding and hiring high-quality software developers easier than with mainstream languages. We have invested deeply in OCaml and intend to use OCaml and grow our team of functional programmers for the foreseeable future.

Contification is a compiler optimization that turns a function that always returns to the same place into a continuation. Compilers for functional languages use contification to expose the control-flow information that is required by many optimizations, including traditional loop optimizations. This paper gives a formal presentation of contification in MLton, a whole-program optimizing Standard ML compiler. We present two existing algorithms for contification in our framework, as well as a new algorithm based on the dominator tree of a program's call graph. We prove that the dominator algorithm is optimal. We present benchmark results on realistic SML programs demonstrating that contification has minimal overhead on compile time and significantly improves run time.

We present a mathematical framework for expressing trust management systems. The framework makes it easier to understand existing systems and to compare them to one another as well as to design new systems. The framework defines the semantics of a trust management engine via a least fixpoint in a lattice, which, in some situations, leads to an efficient implementation. To demonstrate its flexibility, we present KeyNote and SPKI as instantiations by the framework.

In standard control-flow analyses for higher-order languages, a single abstract binding for a variable represents a set of exact bindings, and a single abstract reference cell represents a set of exact reference cells. While such analyses provide useful may-alias information, they are unable to answer mustalias questions about variables and cells, as these questions ask about equality of specific bindings and references.In this paper, we present a novel program analysis for higher-order languages that answers must-alias questions. At every program point, the analysis associates with each variable and abstract cell a cardinality, which is either single or multiple. If variable x is single at program point p, then all bindings for x in the heap reachable from the environment at p hold the same value. If abstract cell r is single at p, then at most one exact cell corresponding to r is reachable from the environment at p.Must-alias information facilitates various program optimizations such as lightweight closure conversion [19]. In addition, must-alias information permits analyses to perform strong updates [3] on abstract reference cells known to be single. Strong updates improve analysis precision for programs that make significant use of state.A prototype implementation of our analysis yields encouraging results. Over a range of benchmarks, our analysis classifies a large majority of the variables as single.

We describe a framework for flow analysis in higher-order languages. It is both a synthesis and extension of earlier work in this area, most notably [20, 22]

According to folklore, Algol is an “orthogonal” extension of a simple imperative programming language with a call-by-name functional language. The former contains assignments, branching constructs, and compound statements; the latter is based on the typed λ-calculus. In an attempt to formalize the claim of “orthogonality”, we define a simple version of Algol and an extended λ-calculus. The calculus includes the full β-rule and rules for the reduction of assignment statements and commands. It has the usual properties, e.g., it satisfies a Church-Rosser and Strong Normalization Theorem. In support of the claim that the imperative and functional components are orthogonal to each other, we show that the proofs of these theorems are combinations of separate Church-Rosser and Strong Normalization theorems for each sublanguage.