ICFP/SPLASH 2025
Sun 12 - Sat 18 October 2025 Singapore
Wed 15 Oct 2025 13:40 - 14:05 at Peony West - Proof we need. Proof! Chair(s): Xavier Rival

Second class values are allocated on the run-time stack and they may contain pointers
to other values on the stack. They were first discussed in connection with the
infamous funarg problem, but then forgotten as heap-allocated closures were
discovered.

Recent work has resurrected the interest in second class values as they allow us
to safely allocate some data structures (e.g., closures) on the run-time stack.
This approach has the advantage of avoiding the cost and the
unpredictable timing of garbage collection for
these structures as their deallocation takes no extra time when the
stack is popped.
A system with qualified types ensures that second class values do not
escape across stack pops.

We take a second look at this work and extend/modify their formal framework
with first-class and second-class references in the style of ML. Along
the way we answer a question that left us mystified in the previous
work: What, exactly, is the meaning of a type qualifier?

Wed 15 Oct

Displayed time zone: Perth change

13:40 - 15:25
Proof we need. Proof!OlivierFest at Peony West
Chair(s): Xavier Rival Inria - CNRS - Ecole Normale Superieure de Paris - PSL University
13:40
25m
Talk
What I Always Wanted to Know about Second Class Valuesfestschrift
OlivierFest
Peter Thiemann University of Freiburg
DOI
14:05
25m
Talk
A Tale of Two Zippersfestschrift
OlivierFest
Philip Wadler IOG; University of Edinburgh, Ramsay Taylor IOG, Jacco Krijnen Utrecht University
DOI
14:30
25m
Talk
Verified Nanopasses for Compiling Conditionalsfestschrift
OlivierFest
Jeremy G. Siek Indiana University
DOI
14:55
15m
Talk
Verifying Effectful Programs via Answer-Type Modification
OlivierFest
Taro Sekiyama National Institute of Informatics
15:10
15m
Talk
From Delimited Continuations to Staged Logics
OlivierFest
Wei-Ngan Chin National University of Singapore, Darius Foo National University of Singapore, Yahui Song Standard Chartered Bank