Type inference is essential for statically-typed languages such as OCaml and Haskell. It can be decomposed into two (possibly interleaved) phases: a generator converts programs to constraints; a solver decides whether a constraint is satisfiable. ...

Deforestation is a compiler optimization that removes intermediate data structure allocations from functional programs to improve their efficiency. This is an old idea, but previous approaches have proved limited or impractical — they either only worked ...

In recent years, dynamic languages such as Python have become popular due to their flexibility and productivity. The lack of static typing makes programs face the challenges of fixing type errors, early bug detection, and code understanding. To alleviate ...

Decompilation is a well-studied area with numerous high-quality tools available. These are frequently used for security tasks and to port legacy code. However, they regularly generate difficult-to-read programs and require a large amount of engineering ...

Type systems typically only define the conditions under which an expression is well-typed, leaving ill-typed expressions formally meaningless. This approach is insufficient as the basis for language servers driving modern programming environments, which ...

Type inference in the presence of first-class or “impredicative” second-order polymorphism à la System F has been an active research area for several decades, with original works dating back to the end of the 80s. Yet, until now many basic problems ...

Control-Flow Integrity (CFI) is considered a promising solution in thwarting advanced code-reuse attacks. While the problem of backward-edge protection in CFI is nearly closed, effective forward-edge protection is still a major challenge. The keystone of ...

A pluggable type system extends a host programming language with type qualifiers. It lets programmers write types like unsigned int, secret string, and nonnull object. Typechecking with pluggable types detects and prevents more errors than the host type ...

Python is a popular dynamic programming language, evidenced by its ranking as the second most commonly used language on GitHub. However, its dynamic type system can lead to potential type errors, leading researchers to explore automatic type inference ...

Julia is a dynamic language for scientific computing. For a dynamic language, Julia is surprisingly typeful. Types are used not only to structure data but also to guide dynamic dispatch – the main design tool in the language. No matter the dynamism,...

As type and effect systems become more expressive there is an increasing need for efficient type inference. We consider a polymorphic effect system based on Boolean formulas where inference requires Boolean unification. Since Boolean unification ...

Creating good type error messages for constraint-based type inference systems is difficult. Typical type error messages reflect implementation details of the underlying constraint-solving algorithms rather than the specific factors leading to type ...

API recommendation has been widely used to enhance developers’ efficiency in software development. However, existing API recommendation methods for dynamic languages such as Python usually suffer from the limitations of incorrect type inference and lack ...

Python programming language has gained enormous popularity in the past decades. While its flexibility significantly improves software development productivity, the dynamic typing feature challenges software maintenance and quality assurance. To ...

Parsing expressions grammars (PEGs) are a recognition-based formalism for language specification, which has been the subject of several research works. A PEG that succeeds or rejects every input string is said to be complete. However, checking if an ...

Symbolic execution (SE) has been widely adopted for automatic program analysis and software testing. Many SE engines (e.g., KLEE or Angr) need to interpret certain Intermediate Representations (IR) of code during execution, which may be slow and ...

Timing side-channels can be exploited to infer secret information when the execution time of a program is correlated with secrets. Recent work has shown that Just-In-Time (JIT) compilation can introduce new timing side-channels in programs even if ...

Recently, Python has adopted optional type annotation to support type checking and program documentation. However, to enjoy the benefits, developers have to manually write type annotations, which is recognized to be a time-consuming task. To alleviate ...

Types in TypeScript play an important role in the correct usage of variables and APIs. Type errors such as variable or function misuse can be avoided with explicit type annotations. In this work, we introduce FlexType, an IDE extension that can be used ...

In the last two years at WhatsApp we have developed eqWAlizer - a type-checker for Erlang AS IS - in style of Flow, Pyre, Hack. It’s already used in a significant part of our codebase. In this talk we overview the key eqWAlizer's design choices we made ...