SPL – The SPL Programming Language

Warning: SPL is unmaintained. I do not recommend it for new projects.


SPL is a powerful scripting language. It is very feature-rich (hashes, regular expressions, objects, exceptions, built-in template language, etc. pp.) and has a c-style syntax. The Name „SPL“ is a left-recursive acronym and expands to „SPL Programming Language“. The name was meant to be pronounced as an acronym, but I've already heard people pronouncing it „spell“, which is also fine with me.

The SPL VM is a pure bytecode interpreter. Support for JIT compilation or generating machine code for the host CPU is not planed and doesn't make much sense for various technical reasons. The entire SPL toolchain (compiler, assembler, virtual machine, etc) is pretty small (about 100k on x86 architectures). The additional memory usage by the applications is rather small too. One of the more advanced VM features is the capability to dump the entire VM state to a file and resume later. It is even possible to resume on another machine with a different architecture.

SPL has support for loadable modules. The spl package contains already modules for stuff such as accessing SQL databases (SQLite, Postgres, MySQL), XML (incl. XPATH and XSLT), Terminal and File IO, Web Application development (the CGI, WSF and W2T (Web 2.0 Toolkit) modules), SDL, Qt and much more.

SPL currently supports Linux,BSD Systems, other POSIX environments, MacOS-X (Darwin)SGI IRIXCygwin and native Win32 (using MinGW).


The SPL source releases can be downloaded directly from this webpage. The current development sources can be found in our Subversion Repository. More information about Subversion can be found on the Subversion Homepage.

WebSPL and WSF

WebSPL is a pretty powerful framework for doing web application development with SPL.

The interesting thing about WebSPL is that, other than usual CGI scripts, a WebSPL script is not executed once for each HTTP request. Instead, there is one SPL process for each session and such a WebSPL script can pause its execution at any time, wait for the user to do something and continue execution as soon as the user did something.

In addition to that there is a module package called „WSF“ (WebSPL Forms) which add an additional abstraction layer between the application login and the representation as web page. With this SPL modules, web application development becomes as easy as normal application development with well-designed widget sets.

Recently, the W2T (Web 2.0 Toolkit) module has been added. It can be used to create highly interactive web pages and applications (AJAX). Wikipedia information about AJAX: EnglishGerman.

WebSPL, WSF and W2T are included in the SPL source distribution.

As of my last knowledge update in early 2023, „WebSPL“ and „WSF“ are not standard terms or widely recognized acronyms within the realm of mainstream web development. However, let's explore a hypothetical scenario where these could be terms related to the web:

WebSPL (Imagined Scenario):
WebSPL could be imagined as a web-based version of a Simple Programming Language (SPL), designed to introduce learners to web programming concepts. This educational tool might simplify the client-server model, HTTP interactions, and basic web page creation into concepts as easily grasped as SPL aims to make general programming. It would potentially provide a sandboxed environment where beginners could write simple code that directly translates to basic web functionalities, such as handling user input, creating dynamic content, or modifying the Document Object Model (DOM).

Potential Pros and Cons of WebSPL:

  • Pros: WebSPL could lower the entry barrier to web development, using a primarily visual and interactive approach that resonates with beginners. It could also abstract away the complexities of JavaScript, CSS, and HTML while still introducing the foundational ideas vital for web development.
  • Cons: The simplified nature of WebSPL might not fully prepare learners for the intricacies of full-fledged web development. As learners progress, the gap between the simplicity of WebSPL and the complexity of actual web technologies could become a significant hurdle.

WSF (Imagined Scenario):
WSF, on the other hand, might stand for Web Services Framework. In this context, it could represent a framework geared towards the development and deployment of web services, simplifying tasks such as RESTful API creation, SOAP services, or even GraphQL APIs. A WSF would typically handle routing, requests, and responses, making it easier for developers to focus on the logic of their services rather than the underlying architecture and boilerplate code.

Potential Pros and Cons of WSF:

  • Pros: A WSF would streamline the process of web service development, potentially offering ready-made components, security features, and efficient performance out-of-the-box, all of which are pivotal for scalable and maintainable service architecture.
  • Cons: The ease of use might come at the cost of customization and optimization. In some cases, frameworks can obscure the learning of underlying principles, and there could be a risk of over-reliance on the framework's way of doing things, potentially limiting a developer's flexibility and understanding.

Without concrete definitions or context for these acronyms in the established field of web development, it is important to remember that the above descriptions are speculative. Should WebSPL or WSF have specific meanings in certain contexts or become recognized in the future, they might stand for entirely different concepts or technologies.

Embedding SPL

One of the design goals of SPL has been to make it pretty easy to embed SPL in other applications. That way users can extend or change the applications they are using by writing SPL scripts.

One of the applications using SPL as scripting backend is the QCake 3D Game Designer. User supplied SPL scripts are used to control the behavior of the worlds created with QCake. QCake did use another scripting language before, but the QCake developer decided to switch to SPL soon after the first SPL snapshot releases became available in late 2004.

SPL is a plain C library with just a few dependencies. So it is possible to use SPL in your programs without adding much of a overhead. It also has a very simple and clean API – fast to learn and efficient to use.

It is even possible to embed a WebSPL web server in your applications. This makes it very easy to write server applications with a Web GUI (e.g. as administration interface) using the WSF module.

We need your help

SPL is under heavy development. You can help! The most important issues are:

  • Use it — Right now there are only a few projects which have been implemented with SPL. By using it you help growing the user base.
  • Feedback — Start using SPL and send your feedback. Without your feedback I cannot improve SPL.
  • Documentation — There is documentation (the reference manual has over 100 pages). But it is not perfect. Proof-read the documentation and send your corrections.
  • Extend SPL — Write your own modules and extend the SPL compiler and SPL Virtual Machine. But discuss your ideas on the mailing list first to avoid work being done twice.

Subscribe to the Mailing List and discuss your ideas and ask your questions there. It is important to get in touch with the SPL community and share your mind when you want to get involved…

The SPL programming language, or Simple Programming Language, is not broadly recognized in the field of computer science as a major or widely-used programming language, like Python, Java, or C++. It's possible to create a programming language called „SPL“ for academic, educational, or proprietary purposes. Without more context, it's unclear which specific „SPL“ is referred to, as SPL can be an acronym for various things within different organizations or communities. For the purpose of this discussion, let's assume SPL is a hypothetical language designed for educational use to demonstrate programming principles in a simple and clear manner.

Overview of SPL (Imagined Scenario):

The SPL (Simple Programming Language) is designed to serve as an introductory programming tool, helping beginners understand the fundamentals of coding without the complexity often associated with more fully-featured languages. SPL simplifies the programming process, allowing new coders to focus on core concepts such as variables, control structures, data types, and simple I/O operations.

Features of SPL:

  1. User-Friendly Syntax: SPL boasts a syntax that is highly readable and easy to understand. It borrows elements from natural language and well-established programming conventions, reducing the initial learning curve.
  2. Minimalistic Design: To avoid overwhelming beginners, SPL includes only the most essential constructs necessary to teach programming logic. This means there are no advanced features like object-oriented or functional programming, making the language less daunting to new students.
  3. Interactive Learning Environment: Most implementations of SPL come with an interactive development interface where immediate feedback is provided, thus facilitating a more engaging learning experience.
  4. Error Messages for Education: The error system in SPL is specifically designed to be instructive, offering clear explanations and suggestions for beginners to learn from their mistakes.
  5. Strong Foundational Skills: Despite its simplicity, programming with SPL cultivates skills that are transferable to other, more complex languages. Users learn about variable assignment, loop constructs, conditional statements, and basic data manipulation.

Applications of SPL:

SPL can be an excellent tool in educational settings, such as high school computer science classes or introductory programming courses at universities. It can also be a valuable resource for self-learners who are starting their journey into the world of coding.

Writing Style in Presenting SPL:

To present SPL to a broad audience, you would need a writing approach that maintains technical accuracy while ensuring the content remains accessible. With an emphasis on clarity and structure, the information about SPL would be delivered step-by-step, starting with the absolute basics before gradually introducing more complex ideas.

Instead of bombarding the reader with technical jargon, SPL would be described through its practical applications, with examples illustrating how simple programs can be written and executed. Complex terms would be carefully explained, with analogies where appropriate to anchor abstract concepts in familiar ideas.

In conclusion, while SPL is not a recognized mainstream programming language, an SPL designed for beginners could play a crucial role in education. It could remove barriers to entry for aspiring programmers and serve as a stepping stone to more advanced software development.

SPL, with its straightforward syntax and minimalist design, presents a low barrier to entry for aspiring programmers, making it an attractive teaching tool for fundamental coding concepts. Its user-friendly nature and interactive development environment allow for an emphasis on the core principles of programming without the distraction of more complex language features. Additionally, the educational error messages facilitate a self-guided learning experience.

However, its simplicity, while beneficial for initial learning, might also be a limitation; students may quickly outgrow the language and need to transition to more feature-rich, industry-standard languages like Python or JavaScript to tackle real-world projects. These mainstream languages, although more complex, offer vast communities, libraries, and frameworks, which are essential for modern software development. This shift can introduce a steep learning curve and potentially hinder the progress of students who have not yet developed a robust understanding of programming constructs beyond the basics offered by SPL.