Philpax

https://fosdem.org/2026/schedule/event/3A7VGM-blue/

• Can run build commands
• Framework to build your own build systems
• Can define your objects and let blueknow what to do
• Why another build system?
  • Blue is minimalist and self-contained
  • Only one dependency; guile
  • Blue can bootstrap itself
  • Blue is goal-based; you specify a goal and blue will figure out what steps are required
  • Blue is extensible
    • GOOPS: method overriding/redefining, inheritance
    • User-defined commands that can override built-in commands
    • Plugin system
    • Stencil system
    • Project serialisation
• Hello blue:
  • Blueprint for gathering a blue project description
  • Stencil for a set of buildable types and utilities to simplify the description of common patterns
  • Buildables for an object that blue knows how to build
  • Put this together into a blueprint
• This fails to begin with, because we need to provide a configuration for this stencil
  • Doing blue configure -- build
  • The double-dash is used to pass arguments to subcommands, like guix
• Configuration:
  • Can define variables for project - version, cflags, etc
  • Project dependencies - can use list mapping to construct it
  • Blue can tell you why thing sfail
  • Example:
    • Start by bringing blue modules
      • Add a C stencil
    • Add CFLAGS variable
    • Add the rest of the state
    • Configure and build
• Delayed computation
  • Expression evaluated at runtime with a dynamic computation environment
  • The application is memoized
  • Expression syntax for doing thisi
  • Syntax sugar for make-computation + lambda
  • Can be used for obtaining configuration values
  • Much more than variable expression; bring the power of Guile, and can be serialised to disk
• Replay functionality to debug how the build failed
• Preference system; can be defined globally, project-locally, or env variable
• Extensibility
  • Inheritance
  • Slots have a type system
  • Method overloading
  • Can define our own buildables
• BLUE.EL - emacs interface for BLUE
• BLUE can bootstrap by pulling itself in as a dependency
• Currently in the pre-alpha phase
• Lots of current features