Semmle Limited

Microsoft Technology Licensing, LLC

Alexander Eyers-Taylor

Max Schaefer

Michael Peyton Jones

Aditya Sharad

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing local distribution heuristics. One of the methods includes receiving an original expression having a conjunction comprising a context term and a disjunction of a plurality of other terms. The context term and the disjunction are evaluated according to one or more local distribution heuristics to determine that the context term is a candidate for distribution across the disjunction of the plurality of other terms. In response, a transformed expression is generated in which the candidate context term is distributed across the disjunction of the plurality of other terms.

Query language distribution heuristics

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for implementing algebraic data types in database query languages. One of the methods includes receiving an expression in a database query language, the expression having a programming language construct representing an algebraic data type, wherein the expression specifies two or more alternative subtypes. Respective domain relations are generated using definitions of each of the alternative subtypes within the expression. Unique domain identifiers are assigned among domain tuples belonging to each alternative subtype. A union relation is generated for the algebraic data type. Unique union identifiers are assigned for union tuples belonging to the union relation. Respective injector relations are generated for each of the alternative subtypes.

Algebraic data types for database query languages

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating identifiers for tuples of recursively defined relations. One of the methods includes selecting one or more of the recursively defined relations to evaluate. Respective keys are computed for each tuple of any new tuples computed during recursive evaluation. For each key that occurs in a cache of keys, obtaining a tuple for the key from the cache and adding the obtained tuple to a new relation. For each key that does not occur in the cache of keys, generating a new identifier for the key, and adding, to a new relation for each key of each tuple of any keys that do not occur in the cache of keys for a relation, a new tuple comprising (1) elements of the tuple and (2) the new identifier for the key.

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Oxford, United Kingdom

Alexander Eyers-Taylor