Tree @0.8 (Download .tar.gz)
Robin
Version 0.8. Work-in-progress, subject to change.
Overview
Robin is an excessively principled and thoroughly specified functional programming language with eager evaluation, latent typing, and a homoiconic syntax, based on a radically simple core semantics in which the so-called "fexpr" is the fundamental abstraction and both functions and macros are defined in terms of it.
Expressions in Robin are referentially transparent; programs interact with the outside world through an event-driven framework.
For more information, see the extended description below.
Quick Start
The Robin reference interpreter is written in about 1300 lines of Haskell.
To use it, you'll need an implementation of Haskell installed (typically either
ghc
or Hugs).
If you have shelf installed, you can just run shelf_dockgh catseye/Robin
.
If not, you can clone this repository, cd
into the repo directory, and run
./build.sh
to build the reference interpreter. (If you don't have ghc
, no executable will
be built, but the bin/robin
script will use runhaskell
or runhugs
instead.)
You can then run it on one of the example Robin sources in eg
like so:
bin/robin pkg/stdlib.robin eg/hello-world.robin
You should see
Hello, world!
To continue learning to program in Robin you can follow The Robin Tutorial.
Testing
If you have a few minutes to spare, and you have Falderal installed, you can run the test suite (consisting of more than 400 unit tests) by running
./test.sh
The tests that use only Robin's core semantics (with no help from implementation "builtins") are quite slow, so you may want to skip them, by running
APPLIANCES="appliances/robin.md" ./test.sh
The test suite will also run some property tests (using QuickCheck). Notably, for every operator that is defined multiple times (which includes much of stdlib, where the core definitions are written in Robin but also implemented in Haskell as "builtins" in the reference interpreter), QuickCheck will attempt to falsify the assertion that the definitions define the same operator. These attempts are currently rather crude; there is lots of room for improvement for them in some future release.
Extended Description
For experienced programmers, Robin might be best described by listing the languages that have had the strongest influences on it:
Scheme
Like Scheme, Robin is eagerly evaluated, latently typed, and homoiconic, as well as properly tail-recursive and lexically scoped (at least by default), and tries hard to be well-defined and system-agnostic, but (as you can read below) diverges significantly from Scheme in other ways.
Forth
Like Forth, Robin has a radically simple core semantics. There are 15 intrinsic operations; every symbol in the standard library is defined in terms of these intrinsics, while an implementation is free to provide its own (perhaps more efficient) implementation of any such symbol. (See also Pixley).
PicoLisp
In most languages, the arguments to a function are evaluated before the function is applied, but PicoLisp allows defining functions with unevaluated arguments. In historical Lisp, such operators were called fexprs. Robin adopts fexprs as the fundamental abstraction — both functions and macros are defined in terms of fexprs.
The Kernel programming language also takes fexprs as its fundamental abstraction; however, Robin was developed oblivious of Kernel — it adapted the idea directly from PicoLisp.
Haskell
Like Haskell, Robin is referentially transparent (often described as "purely functional") — mutation of values is forbidden. (Robin intentionally does not, however, adopt lazy evaluation or a static type system.)
Elm
Interactive programs in Robin are built by composing transducers which are driven by events and produce effects (which are modelled as further events), in a manner very similar to The Elm Architecture.
Bourne shell
Arbitrary text can by embedded in a Robin program using a syntax very much like a "heredoc", except it is an S-expression.
English
Deserves at least a passing mention here, as one thing that Robin
discards from Scheme is its jargony terminology: no cdr
, no cons
,
no lambda
. (A notable exception is fexpr
simply because there is no
satisfying short, non-jargony word that connotes how these operators work.)
For a full description of the Robin language, see the Robin specification document.
Repository Layout
appliances/
— test appliances for the literate test suite.bin/
— driver script, destination for executable when built.demo/
— contains HTML5 document demonstrating build to JS by Haste.doc/
— Tutorial, specification, rationale, etc.eg/
— example programs written in Robinsrc/
— Haskell source for reference interpreter.stdlib/
— normative definitions of standard library symbols.HISTORY.md
— history of this distribution.TODO.md
— plans.
Commit History
@0.8
git clone https://git.catseye.tc/Robin/
- Merge pull request #7 from cpressey/develop-0.8 Chris Pressey (commit: GitHub) 3 years ago
- Add "Detecting Errors in Robin" document. Chris Pressey 3 years ago
- Updates to TODO and HISTORY. Chris Pressey 3 years ago
- Update "macro" to "fexpr" in tutorial and rationale document too. Chris Pressey 3 years ago
- Fix indentation and version number. Chris Pressey 3 years ago
- Rewrite `itoa` and `not` as functions. Chris Pressey 3 years ago
- Define arithmetic functions with functions. Chris Pressey 3 years ago
- Rewrite definitions of comparators as functions. Chris Pressey 3 years ago
- Rewrite boolean operators as functions. Chris Pressey 3 years ago
- Note down an idea. Chris Pressey 3 years ago