Type-Based Cost Analysis for Lazy Functional Languages

• Type: Article in International Scientific Journal
• Date: 2017-06-01

Authors

Florido, M (Author) FCUP; Pedro Vasconcelos (Author) FCUP; Steffen Jost (Author) Other; Kevin Hammond (Author) Other

Journal

Title: Journal of Automated Reasoning

Vol. 59 No. 1

Pages: 87-120

ISSN: 0168-7433

Publisher: Springer Nature

Indexing

ISI Web of Knowledge - 16 Citations

ISI Web of Science

Scopus - 18 Citations

Other information

Authenticus ID: P-00M-BG3

DOI: 10.1007/s10817-016-9398-9

Abstract (EN): We present a static analysis for determining the execution costs of lazily evaluated functional languages, such as Haskell. Time- and space-behaviour of lazy functional languages can be hard to predict, creating a significant barrier to their broader acceptance. This paper applies a type-based analysis employing amortisation and cost effects to statically determine upper bounds on evaluation costs. While amortisation performs well with finite recursive data, we significantly improve the precision of our analysis for co-recursive programs (i.e. dealing with potentially infinite data structures) by tracking self-references. Combining these two approaches gives a fully automatic static analysis for both recursive and co-recursive definitions. The analysis is formally proven correct against an operational semantic that features an exchangeable parametric cost-model. An arbitrary measure can be assigned to all syntactic constructs, allowing to bound, for example, evaluation steps, applications, allocations, etc. Moreover, automatic inference only relies on first-order unification and standard linear programming solving. Our publicly available implementation demonstrates the practicability of our technique on editable non-trivial examples.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 34