2007 (for 1997):
Functional
Reactive Animation, Conal Elliott and Paul Hudak
Citation
"Functional Reactive Animation" by
Conal Elliott and Paul Hudak was the first published paper on functional
reactive programming. It described a collection of data types and functions
that comprised an embedded domain-specific language called Fran for
composing interactive, multi-media animations. The key abstractions were
first-class behaviors and events. Intuitively, a behavior is a value that
varies with continuous time while an event is a discrete counterpart
including time-varying predicates. The idea of regarding the entire lifetime
of a time-varying quantity as a single first-class value was new and very
surprising at the time, but the paper made it seem simple and obvious. The
insight in the paper led to a significant number of follow-on projects
including FranTk, Fruit, Pidgets, FrTime, Frob, FRP, Frappe, Frag, Fvision,
Yampa, Feris, and work on embodying financial contracts in functional terms.
2006 (for 1996):
Optimality and
inefficiency: what isn't a cost model of the lambda calculus?, Julia L.
Lawall and Harry G. Mairson
Citation
Julia Lawall and Harry Mairson's 1996
ICFP paper "Optimality and inefficiency: What isn't a cost model of the
lambda calculus?" exposed a fundamental problem with proposed algorithms for
optimal reduction. Starting with Jean-Jacques Lévy's seminal work in 1978,
the goal of optimal reduction was to correctly normalize lambda-calculus
terms without duplicating redexes. Various strategies were subsequently
devised to realize optimal reduction, notably the solution of John Lamping
at POPL 1990, then simplified and improved by Georges Gonthier, Martín Abadi,
and Jean-Jacques Lévy at POPL 1992. Each solution used subtle bookkeeping
mechanisms to control sharing.
Lawall and Mairson showed that these
bookkeeping mechanisms introduced a complexity and inefficiency of their
own. They discovered terms that could be normalized in linear time, but
whose bookkeeping costs required exponential time. They further showed that
Frandsen and Sturtivant's cost model for lambda-calculus reduction,
presented at FPCA 1991, needed to account for the size of intermediate
terms, and that optimal-evaluation interpreters were at least exponentially
slower than the proposed cost model. Lawall and Mairson concluded that the
notion of optimality did not necessarily coincide with that of efficiency.
As a consequence, different and possibly optimal evaluation strategies were
still needed, as were more realistic cost models. Subsequent work in this
area has focused on such cost models, on further analysis of the inherent
complexity of optimal reduction, and on relaxing the optimality condition in
exchange for lower bookkeeping overhead and greater overall efficiency.
