Sysel

An effort to design a high-level programming language for writing HelenOS severs and applications.

• ​Sysel project at launchpad
• ​Examples of real (working) Sysel code
• Description of planned features and ideas

Note that Sysel syntax is not finalized. Some important language features are missing at the moment (especially visibility control and packaging) so the examples presented will need to change when these are implemented.

This article currently serves several purposes. First as a memo, not to forget ideas and elaborations. Second as a temporary source of information for anyone who wants to learn about Sysel (and plans for it). Third by sharing the plans to allow discussion and brainstorming.

Roadmap

Sub-project name	Status	Description
Sysel Bootstrap Interpreter (SBI)	In progress	Interpreter of Sysel written in C. Runs in HelenOS and POSIX.
Sysel Compiler Toolkit (NNPS)	Not started	Modular compiler of Sysel written in Sysel itself. To produce C and/or LLVM IR.

SBI

SBI is an interpreter of Sysel currently in development. It is available stand-alone for POSIX or bundled with HelenOS (only in Bazaar repository, not yet in a stable release). You can run it with the command "sbi source_file.sy". Demos that you can run are available in /src/sysel/demos. Source files comprising the library are in /src/sysel/lib.

You can also run sbi without parameters to enter interactive mode.

Synopsis of current SBI features

• Primitive types: bool, char, int, string
• Compound types: class, multi-dimensional array
• Other types: delegates, enumerations
• Objective features: constructors, inheritance, grandfather class, static and non-static method invocation
• Syntactic sugar: variadic functions, accessor methods (named and indexed properties), autoboxing
• Arithmetic: big integers, addition, subtraction, multiplication, boolean operators
• Static type checking (mostly), generic classes (unconstrained), exception handling
• Bindings: Text file I/O, WriteLine, Exec

Missing SBI features

• division
• structs
• interfaces
• builtin object methods/properties
• static class variables
• visibility control
• working with binary data

• generic type constraints
• method and operator overloading
• code organization (packages and modules)

NNPS

NNPS (Nativní Nástroje pro Překlad Syslu, en: Native Sysel Compilation Toolkit) is a prospective toolkit written in Sysel itself that should compile Sysel to binary form. Currently it is in preliminary experimentation/planning stage. Also current plan is to only implement a front end, transforming Sysel into low-level but machine-neutral IR. Most likely the first available output option should be C (used as if it were a machine-independent assembly) and the second LLVM IR. The native in NNPS means it is written in Sysel itself (i.e. it should be also self-hosting).

Ideally NNPS should compile natively in POSIX, cross-compile from POSIX to HelenOS and eventually compile natively in HelenOS. The eventually is there because an appropriate backend (i.e. a C compiler) needs to be ported to HelenOS before native compilation is feasible.