NEWS.md

In arl: Embedded Lisp Dialect

arl 0.1.4

Performance

• Reduce CRAN test runtime via uniform test thinning: on CRAN, run every 3rd test block per file (controlled by make_cran_thinner(keep_every = 3L)), cutting ~67% of per-test work while keeping full coverage off CRAN.
• Reduce TCO test recursion depth on CRAN (6000 vs 10000) to further cut runtime while still validating tail-call optimization well beyond R's default stack limit.

arl 0.1.3

CRAN Compliance

• Remove "for R" from package title per CRAN policy.
• Replace bare cat() calls with S3 print methods (arl_cli_output, arl_help_doc, arl_coverage_report) so console output follows CRAN guidelines.
• Require explicit output_file argument in report_html() and report_json() — no longer write to the working directory by default.
• Convert example vignette code chunks from {r} read-and-cat wrappers to {arl} chunks that execute via the knitr engine.

arl 0.1.2

Performance

• Pre-build vignettes in the tarball using the .Rmd.orig + stub pattern, cutting ~110s from R CMD check vignette rebuild time.
• Speed up test suite by avoiding stdlib prelude loading in tests that don't need it.
• Reduce TCO test recursion depth to reduce runtime while still checking deeper recursion than R's defaults allow.

Bug Fixes

• Fix multiple temporary file and connection leaks uncovered by stricter CRAN-like checking.
• make install now ships pre-built vignettes (previously installed without them).

Infrastructure

• make check now mirrors CRAN settings more closely and prints wall-clock time for the R CMD check step.
• CI fetches gh-pages branch so benchmark data is available during vignette rendering.

arl 0.1.1

Bug Fixes

• Fixed stale module cache poisoning when ambient macros differ between sessions. The module cache now computes a fingerprint of all macros visible in a module's parent environment chain (not just the prelude) and invalidates entries when macros change.
• Fixed missing dependency declaration in looping.arl.
• Fixed Windows backslash path handling in tests.
• Fixed FileDeps tests to work during R CMD check.
• Fixed bad URLs in README and vignettes.
• Included vignette files in built tarballs (.Rbuildignore fix).

Testing

• Tests now disallow unexpected/unhandled warnings.
• Added make coverage-test-file target for single-file coverage testing.

arl 0.1.0

Initial release of arl, a Scheme-inspired Lisp dialect embedded in R.

Language

• Special forms: quote, if, define, set!, lambda, begin, defmacro, quasiquote/unquote/unquote-splicing, and, or, while, delay, import, and module.
• Truthiness: #f, #nil, and 0 are falsy; everything else is truthy.
• Cons cells: First-class dotted pairs, with both cons-cell and R-native list representations.
• Destructuring: Pattern destructuring in define, set!, let, and lambda, including nested patterns, rest parameters, and defaults.
• Multiple values: values and call-with-values.
• Continuations: call-cc via R's native callCC.

Macro System

• Compile-time code transformation with quasiquotation templates.
• Hygiene via gensym and capture.
• Introspection with macro?, macroexpand, macroexpand-1, and macroexpand-all.
• Documentation attachment via ;;' comments.

Module System

• Named and anonymous modules with explicit or export-all exports.
• Qualified access via / syntax (e.g. math/inc).
• Import modifiers: :refer, :as, :rename, :reload.
• Modules are first-class environment objects with locked bindings.
• Re-export support, circular dependency detection, and module caching.
• Introspection: module?, module-name, module-exports, module-ref.

Compiler

• Single-pass compilation from Arl to R expressions.
• Self-tail-call optimization: rewrites self-recursive functions in tail position as while loops.
• Constant folding, dead code elimination, strength reduction, identity lambda elimination, boolean flattening, and arithmetic infix compilation.

Standard Library

22 modules (~800 definitions) auto-loaded via a prelude:

• Core and logic: when, unless, cond, error handling, identity.
• Types and equality: Full suite of type predicates; equal?, eqv?, eq?.
• List and sequences: append, reverse, take, drop, nth, range, repeat, cycle, zip, and more.
• Functional: map, filter, reduce, fold, compose, partial, juxt, complement, constantly.
• Control flow: try-catch, finally, condition signaling and handling.
• Binding forms: let, let*, letrec with destructuring.
• Threading macros: ->, ->>, as->, some->, some->>, cond->, cond->>.
• Looping: until, do-list, Clojure-style loop/recur.
• Math: inc, dec, abs, sqrt, trigonometric functions, and more.
• Strings: str, string-concat, string-split, and friends.
• I/O: File reading/writing, display, and formatting.
• Data structures: Hash-backed dict and set types with full operation suites; defstruct macro for S3-backed record types.
• Sorting: list-sort, sort-by, merge-sorted, stable-sort.
• Assertions: assert-equal, assert-true, assert-false, and others.

R Interoperability

• Direct access to all R base and default-package functions.
• Keyword arguments (:name value), formulas, $, [, [[, and @.
• r-eval and r-call for dynamic R evaluation.
• Bidirectional data exchange: define R objects into Arl, extract results back to R.
• Configurable R package visibility.

Developer Tools

• REPL: Interactive prompt with multi-line input, readline history, bracketed paste, and error recovery.
• CLI: Script execution, --eval expressions, quiet mode, bare engine mode, and stdin support.
• Help system: (help topic) dispatches to special forms, builtins, stdlib docstrings, or R help. doc and doc! for programmatic access.
• Coverage tracking: Line-level and branch-level instrumentation with console, HTML, and JSON reports.
• Knitr engine: {arl} code chunks in R Markdown with persistent engine state and syntax highlighting.

Documentation

• Vignettes: getting started, standard library reference, compiler and internals, and troubleshooting.

arl documentation built on March 19, 2026, 5:09 p.m.