The Programming Language Ceu (v0.5)

Ceu is a synchronous programming language that reconciles Structured Concurrency with Event-Driven Programming in order to extend classical structured programming with three main functionalities:

• Structured Deterministic Concurrency:
  • A set of structured primitives to lexically compose concurrent tasks (e.g., spawn, par-or, toggle).
  • A synchronous and deterministic scheduling policy, which provides predictable behavior and safe abortion of tasks.
  • A container primitive to hold dynamic tasks, which automatically releases them as they terminate.
• Event Signaling Mechanisms:
  • An await primitive to suspend a task and wait for events.
  • A broadcast primitive to signal events and awake awaiting tasks.
• Lexical Memory Management (experimental):
  • A lexical policy to manage dynamic allocation automatically.
  • A set of strict escaping rules to preserve structured reasoning.
  • A reference-counter collector for deterministic reclamation.

Ceu is inspired by Esterel and Lua.

Follows a summary of the main ideas in the design of Ceu:

• https://github.com/fsantanna/dceu/blob/main/doc/manual-out.md#1-design

Follows an extended list of functionalities in Ceu:

• Dynamic typing
• Statements as expressions
• Dynamic collections (tuples, vectors, and dictionaries)
• Stackless coroutines (the basis of tasks)
• Restricted closures (upvalues must be final)
• Deferred statements (for finalization)
• Exception handling (error & catch)
• Hierarchical Tags and Tuple Templates (for data description)
• Seamless integration with C (source-level compatibility)

Ceu is in experimental stage. Both the compiler and runtime can become very slow.

Hello World!

During 10 seconds, displays Hello World! every second:

spawn {
    watching <10:s> {
        every <1:s> {
            println("Hello World!")
        }
    }
}

Manual

• https://github.com/fsantanna/dceu/blob/main/doc/manual-out.md

Install

1. Install gcc and java:

sudo apt install gcc default-jre

2. Install ceu:

wget https://github.com/fsantanna/dceu/releases/download/v0.5.0/install-v0.5.0.sh
sh install-v0.5.0.sh ./ceu/

• We assume that you add ./ceu/ (the full path) to your environment $PATH.

3. Execute ceu:

ceu ./ceu/hello-world.ceu
hello
world

pico-ceu

The best way to try Ceu is through pico-ceu, a graphical library based on SDL:

• https://github.com/fsantanna/pico-ceu

Resources

• A toy Problem: Drag, Click, or Cancel
  • https://fsantanna.github.io/toy.html
  • Run with pico-ceu in ceu/pico/tst/:
    • ceu --lib=pico click-drag-cancel-x.ceu
• Comparison with JS generators:
  • https://github.com/fsantanna/dceu/blob/main/src/test/kotlin/tst_99/JS_99.kt
• A simple but complete 2D game in Ceu:
  • https://github.com/fsantanna/pico-ceu-rocks
  • Clone in ceu/pico/, cd to it, and run with pico-ceu:
    • ceu --lib=pico main.ceu
• Academic publications:
  • http://ceu-lang.org/chico/#ceu
• Mailing list (JOIN US!):
  • https://groups.google.com/g/ceu-lang