ICFP 2021 is the 26th ACM SIGPLAN International Conference on Functional Programming. ICFP 2021 will be virtual.

Research Papers: Call for Papers

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PACMPL issue ICFP 2021 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, and from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects, concurrency, or parallelism. Topics of interest include (but are not limited to):

• Language Design: concurrency, parallelism, and distribution; modules; components and composition; metaprogramming; macros; pattern matching; type systems; type inference; dependent types; session types; gradual typing; refinement types; interoperability; domain-specific languages; imperative programming; object-oriented programming; logic programming; probabilistic programming; reactive programming; generic programming; bidirectional programming.

• Implementation: abstract machines; virtual machines; interpretation; compilation; compile-time and run-time optimization; garbage collection and memory management; runtime systems; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components, or low-level machine resources.

• Software-Development Techniques: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling; build systems; program synthesis.

• Foundations: formal semantics; lambda calculus; program equivalence; rewriting; type theory; logic; category theory; monads; continuations; control; state; effects; names and binding; program verification.

• Analysis and Transformation: control flow; data flow; abstract interpretation; partial evaluation; program calculation.

• Applications: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed systems and web programming; hardware design; databases; XML processing; scientific and numerical computing; graphical user interfaces; graphics and multimedia; GPU programming; scripting; system administration; security.

• Education: teaching introductory programming; parallel programming; mathematical proof; algebra.

Submissions will be evaluated according to their relevance, correctness, significance, originality, and clarity. Each submission should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience.

PACMPL issue ICFP 2021 also welcomes submissions in two separate categories — Functional Pearls and Experience Reports — that must be marked as such when submitted and that need not report original research results. Detailed guidelines on both categories are given at the end of this call.

Please contact the associate editor if you have questions or are concerned about the appropriateness of a topic.

About PACMPL

Proceedings of the ACM on Programming Languages (PACMPL https://pacmpl.acm.org/) is a Gold Open Access journal publishing research on all aspects of programming languages, from design to implementation and from mathematical formalisms to empirical studies. Each issue of the journal is devoted to a particular subject area within programming languages and will be announced through publicized Calls for Papers, like this one.

Preparation of submissions

Deadline: The deadline for submissions is Tuesday, March 2, 2021, Anywhere on Earth (https://www.timeanddate.com/time/zones/aoe). This deadline will be strictly enforced.

Formatting: Submissions must be in PDF format, printable in black and white on US Letter sized paper, and interpretable by common PDF tools. All submissions must adhere to the “ACM Small” template that is available (in both LaTeX and Word formats) from https://www.acm.org/publications/authors/submissions.

There is a limit of 25 pages for a full paper or Functional Pearl and 12 pages for an Experience Report; in either case, the bibliography will not be counted against these limits. Submissions that exceed the page limits or, for other reasons, do not meet the requirements for formatting, will be summarily rejected. Supplementary material can and should be separately submitted (see below).

See also PACMPL’s Information and Guidelines for Authors at https://pacmpl.acm.org/authors.cfm.

Submission: Submissions will be accepted at https://icfp21.hotcrp.com/

Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface.

Author Response Period: Authors will have a 72-hour period, starting at 17:00 UTC on Tuesday, April 20, 2021, to read reviews and respond to them.

Supplementary Material: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. This supplementary material should not be submitted as part of the main document; instead, it should be uploaded as a separate PDF document or tarball.

Supplementary material should be uploaded at submission time, not by providing a URL in the paper that points to an external repository.

Authors are free to upload both anonymized and non-anonymized supplementary material. Anonymized supplementary material will be visible to reviewers immediately; non-anonymized supplementary material will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s).

Authorship Policies: All submissions are expected to comply with the ACM Policies for Authorship that are detailed at https://www.acm.org/publications/authors/information-for-authors.

Republication Policies: Each submission must adhere to SIGPLAN’s republication policy, as explained on the web at http://www.sigplan.org/Resources/Policies/Republication.

Review Process

This section outlines the two-stage process with lightweight double-blind reviewing that will be used to select papers for PACMPL issue ICFP 2021. We anticipate that there will be a need to clarify and expand on this process, and we will maintain a list of frequently asked questions and answers on the PACMPL issue website to address common concerns.

PACMPL issue ICFP 2021 will employ a two-stage review process. The first stage in the review process will assess submitted papers using the criteria stated above and will allow for feedback and input on initial reviews through the author response period mentioned previously. As a result of the review process, a set of papers will be conditionally accepted and all other papers will be rejected. Authors will be notified of these decisions on May 7, 2021.

Authors of conditionally accepted papers will be provided with committee reviews along with a set of mandatory revisions. After four weeks (June 4, 2021), the authors will provide a second submission. The second and final reviewing phase assesses whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. The intent and expectation is that the mandatory revisions can be addressed within four weeks and hence that conditionally accepted papers will in general be accepted in the second phase.

The second submission should clearly identify how the mandatory revisions were addressed. To that end, the second submission must be accompanied by a cover letter mapping each mandatory revision request to specific parts of the paper. The cover letter will facilitate a quick second review, allowing for confirmation of final acceptance within two weeks. Conversely, the absence of a cover letter will be grounds for the paper’s rejection.

PACMPL issue ICFP 2021 will employ a lightweight double-blind reviewing process. To facilitate this, submitted papers must adhere to two rules:

1. author names and institutions must be omitted, and
2. references to authors’ own related work should be in the third person (e.g., not “We build on our previous work …” but rather “We build on the work of …”).

The purpose of this process is to help the reviewers come to an initial judgement about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas.

Information for Authors of Accepted Papers

• As a condition of acceptance, final versions of all papers must adhere to the new ACM Small format. The page limit for the final versions of papers will be increased by two pages to help authors respond to reviewer comments and mandatory revisions: 27 pages plus bibliography for a regular paper or Functional Pearl, 14 pages plus bibliography for an Experience Report.

• Authors of accepted submissions will be required to agree to one of the three ACM licensing options: open access on payment of a fee (recommended, and SIGPLAN can cover the cost as described next); copyright transfer to ACM; or retaining copyright but granting ACM exclusive publication rights. Further information about ACM author rights is available from http://authors.acm.org.

• PACMPL is a Gold Open Access journal, and authors are encouraged to publish their work under a CC-BY license. Gold Open Access guarantees permanent free online access to the definitive version in the ACM Digital Library, and the recommended CC-BY option also allows anyone to copy and distribute the work with attribution. Gold Open Access has been made possible by generous funding through ACM SIGPLAN, which will cover all open access costs in the event authors cannot. Authors who can cover the costs may do so by paying an Article Processing Charge (APC). PACMPL, SIGPLAN, and ACM Headquarters are committed to exploring routes to making Gold Open Access publication both affordable and sustainable.

• ACM offers authors a range of copyright options, one of which is Creative Commons CC-BY publication; this is the option recommended by the PACMPL editorial board. A reasoned argument in favour of this option can be found in the article Why CC-BY? published by OASPA, the Open Access Scholarly Publishers Association.

• ACM Author-Izer is a unique service that enables ACM authors to generate and post links on either their home page or institutional repository for visitors to download the definitive version of their articles from the ACM Digital Library at no charge. Downloads through Author-Izer links are captured in official ACM statistics, improving the accuracy of usage and impact measurements. Consistently linking to the definitive version of an ACM article should reduce user confusion over article versioning. After an article has been published and assigned to the appropriate ACM Author Profile pages, authors should visit http://www.acm.org/publications/acm-author-izer-service to learn how to create links for free downloads from the ACM DL.

• The official publication date is the date the papers are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work.

• Authors of each accepted submission are invited to attend and be available for the presentation of that paper at the conference. The schedule for presentations will be determined and shared with authors after the full program has been selected.

Artifact Evaluation

Authors of papers that are conditionally accepted in the first phase of the review process will be encouraged (but not required) to submit supporting materials for Artifact Evaluation. These items will then be reviewed by an Artifact Evaluation Committee, separate from the paper Review Committee, whose task is to assess how the artifacts support the work described in the associated paper. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Authors of accepted papers will be encouraged to make the supporting materials publicly available upon publication of the papers, for example, by including them as “source materials” in the ACM Digital Library. An additional seal will mark papers whose artifacts are made available, as outlined in the ACM guidelines for artifact badging.

Participation in Artifact Evaluation is voluntary and will not influence the final decision regarding paper acceptance.

Special categories of papers

In addition to research papers, PACMPL issue ICFP solicits two kinds of papers that do not require original research contributions: Functional Pearls, which are full papers, and Experience Reports, which are limited to half the length of a full paper. Authors submitting such papers should consider the following guidelines.

Functional Pearls

A Functional Pearl is an elegant essay about something related to functional programming. Examples include, but are not limited to:

• a new and thought-provoking way of looking at an old idea

• an instructive example of program calculation or proof

• a nifty presentation of an old or new data structure

• an interesting application of functional programming techniques

• a novel use or exposition of functional programming in the classroom

While pearls often demonstrate an idea through the development of a short program, there is no requirement or expectation that they do so. Thus, they encompass the notions of theoretical and educational pearls.

Functional Pearls are valued as highly and judged as rigorously as ordinary papers, but using somewhat different criteria. In particular, a pearl is not required to report original research, but, it should be concise, instructive, and entertaining. A pearl is likely to be rejected if its readers get bored, if the material gets too complicated, if too much specialized knowledge is needed, or if the writing is inelegant. The key to writing a good pearl is polishing.

A submission that is intended to be treated as a pearl must be marked as such on the submission web page, and should contain the words “Functional Pearl” somewhere in its title or subtitle. These steps will alert reviewers to use the appropriate evaluation criteria. Pearls will be combined with ordinary papers, however, for the purpose of computing the conference’s acceptance rate.

Experience Reports

The purpose of an Experience Report is to help create a body of published, refereed, citable evidence that functional programming really works – or to describe what obstacles prevent it from working.

Possible topics for an Experience Report include, but are not limited to:

• insights gained from real-world projects using functional programming

• comparison of functional programming with conventional programming in the context of an industrial project or a university curriculum

• project-management, business, or legal issues encountered when using functional programming in a real-world project

• curricular issues encountered when using functional programming in education

• real-world constraints that created special challenges for an implementation of a functional language or for functional programming in general

An Experience Report is distinguished from a normal PACMPL issue ICFP paper by its title, by its length, and by the criteria used to evaluate it.

• Both in the papers and in any citations, the title of each accepted Experience Report must end with the words “(Experience Report)” in parentheses. The acceptance rate for Experience Reports will be computed and reported separately from the rate for ordinary papers.

• Experience Report submissions can be at most 12 pages long, excluding bibliography.

• Each Experience Report accepted to the PACMPL issue will be presented at the conference, but depending on the number of Experience Reports and regular papers accepted, authors of Experience reports may be asked to give shorter talks.

• Because the purpose of Experience Reports is to enable our community to accumulate a body of evidence about the efficacy of functional programming, an acceptable Experience Report need not add to the body of knowledge of the functional-programming community by presenting novel results or conclusions. It is sufficient if the Report states a clear thesis and provides supporting evidence. The thesis must be relevant to the PACMPL issue, but it need not be novel.

The review committee will accept or reject Experience Reports based on whether they judge the evidence to be convincing. Anecdotal evidence will be acceptable provided it is well argued and the author explains what efforts were made to gather as much evidence as possible. Typically, more convincing evidence is obtained from papers which show how functional programming was used than from papers which only say that functional programming was used. The most convincing evidence often includes comparisons of situations before and after the introduction or discontinuation of functional programming. Evidence drawn from a single person’s experience may be sufficient, but more weight will be given to evidence drawn from the experience of groups of people.

An Experience Report should be short and to the point: it should make a claim about how well functional programming worked on a particular project and why, and produce evidence to substantiate this claim. If functional programming worked in this case in the same ways it has worked for others, the paper need only summarize the results; the main part of the paper should discuss how well it worked and in what context. Most readers will not want to know all the details of the project and its implementation, but the paper should characterize the project and its context well enough so that readers can judge to what degree this experience is relevant to their own projects. The paper should take care to highlight any unusual aspects of the project. Specifics about the project are more valuable than generalities about functional programming; for example, it is more valuable to say that the team delivered its software a month ahead of schedule than it is to say that functional programming made the team more productive.

If the paper not only describes experience but also presents new technical results, or if the experience refutes cherished beliefs of the functional-programming community, it may be better to submit it as a full paper, which will be judged by the usual criteria of novelty, originality, and relevance. The associate editor will be happy to advise on any concerns about which category to submit to.