The Safety of Call Arity

Joachim Breitner 🌐

February 20, 2015

This is a development version of this entry. It might change over time and is not stable. Please refer to release versions for citations.


We formalize the Call Arity analysis, as implemented in GHC, and prove both functional correctness and, more interestingly, safety (i.e. the transformation does not increase allocation).

We use syntax and the denotational semantics from the entry "Launchbury", where we formalized Launchbury's natural semantics for lazy evaluation.

The functional correctness of Call Arity is proved with regard to that denotational semantics. The operational properties are shown with regard to a small-step semantics akin to Sestoft's mark 1 machine, which we prove to be equivalent to Launchbury's semantics.

We use Christian Urban's Nominal2 package to define our terms and make use of Brian Huffman's HOLCF package for the domain-theoretical aspects of the development.


BSD License


March 16, 2015
This entry now builds on top of the Launchbury entry, and the equivalency proof of the natural and the small-step semantics was added.


Session Call_Arity