This product is developed at the second-grade course, Informatic Science
Basic Experiment class at the University of Tokyo.

Picrin - a lightweight scheme interpreter

Features

• R7RS compatibility (but partial support)
• reentrant design (all VM states are stored in single global state object)
• bytecode interpreter (based on Stack VM)
• direct threaded VM
• Internal representation by Nan-Boxing
• conservative call/cc implementation (users can freely interleave native stack with VM stack)
• exact GC (simple mark and sweep, partially reference count is used as well)
• advanced REPL support (multi-line input, etc)
• tiny & portable library (all functions will be in libpicrin.so)

Compliance with R7RS

section	status	comments
2.2 Whitespace and comments	incomplete	block comments are not implemented
2.3 Other notations	incomplete	#e #i #b #o #d #x
2.4 Datum labels	no	unsupported
3.1 Variables, syntactic keywords, and regions
3.2 Disjointness of types	yes
3.3 External representations
3.4 Storage model	yes
3.5 Proper tail recursion	incomplete	apply, call/cc, call/values, eval are not yet
4.1.1 Variable references	yes
4.1.2 Literal expressions	yes
4.1.3 Procedure calls	yes	In picrin () is self-evaluating
4.1.4 Procedures	yes
4.1.5 Conditionals	yes	In picrin (if #f #f) returns #f
4.1.6 Assignments	yes
4.1.7 Inclusion	no	include and include-ci
4.2.1 Conditionals	incomplete	TODO: cond-expand
4.2.2 Binding constructs	incomplete	TODO: let-values, let*-values
4.2.3 Sequencing	yes
4.2.4 Iteration	yes	TODO: do is unsafe when nested
4.2.5 Delayed evaluation	N/A
4.2.6 Dynamic bindings	no	TODO: make-parameter, parameterize in C level
4.2.7 Exception handling	no	guard syntax.
4.2.8 Quasiquotation	incomplete	nested is unsupported
4.2.9 Case-lambda	N/A
4.3.1 Bindings constructs for syntactic keywords	no	Instead, picrin provides so-called legacy macro (define-macro).
4.3.2 Pattern language	--	see above.
4.3.3 Signaling errors in macro transformers	--	see above.
5.1 Programs	yes
5.2 Import declarations	no
5.3.1 Top level definitions	yes
5.3.2 Internal definitions	yes	TODO: interreferential definitions
5.3.3 Multiple-value definitions	no
5.4 Syntax definitions	--	see notes on section 4.3.1.
5.5 Recored-type definitions	no
5.6.1 Library Syntax	no
5.6.2 Library example	N/A
5.7 The REPL	yes
6.1 Equivalence predicates	yes
6.2.1 Numerical types	yes	picrin has only two types of internal representation of numbers: fixnum and double float. It still comforms the R7RS spec.
6.2.2 Exactness	yes
6.2.3 Implementation restrictions	yes
6.2.4 Implementation extensions	yes
6.2.5 Syntax of numerical constants	yes
6.2.6 Numerical operations	yes	denominator, numerator, and rationalize are not supported for now. Also, picrin does not provide complex library procedures.
6.2.7 Numerical input and output	no
6.3 Booleans	yes
6.4 Pairs and lists	yes
6.5 Symbols	yes
6.6 Characters	yes
6.7 Strings	yes	substring is not provided
6.8 Vectors	yes
6.9 Bytevectors	incomplete	TODO: string<->utf8 conversion, etc
6.10 Control features	incomplete	TODO: string-map, vector-map, ...etc
6.11 Exceptions	yes	TODO: native error handling
6.12 Environments and evaluation	N/A
6.13 Ports	incomplete
6.14 System interface	incomplete	exit is unsafe when used with dynamic-wind

Homepage

Currently picrin is hosted on Github. You can freely send a bug report or pull-request, and fork the repository.

https://github.com/wasabiz/picrin

How to use it

• debug-run

  By default make command runs REPL with all debug flags enabled (PIC_GC_STRESS, VM_DEBUG, DEBUG).

    $ make
  

• build

    $ make build
  

  built executable binary will be under bin/ directory and shared library libpicrin.so under lib/.

  If you want to build picrin on other systems than x86_64, make sure PIC_NAN_BOXING flag is turned off (see include/config.h for detail).

• run

  Simply directly run the binary bin/picrin from terminal, or you can use make to execute it like this.

    $ make run
  

In the default option, when make command is called without arguments, it builds the binary and right after that dropped into the picrin interactive shell (REPL).

• install

  As of now picrin does not provide a command automatically installs the binary. If you want to place picrin library and binary in a parmanent directory, please do it by hand.

Requirement

picrin scheme depends on some external libraries to build the binary:

• bison
• yacc
• make
• gcc
• readline

The compilation is tested only on Mac OSX. I think (or hope) it'll be ok to compile and run on other operating systems such as Linux or Windows, but there's no guarantee :(

Authors

Yuichi Nishiwaki (yuichi.nishiwaki at gmail.com)