Limits & Constraints

Thorn is intentionally designed to be small, predictable, and deterministic. It enforces explicit design boundaries:

Identifier & Path Rules

• No Whitespace: Thorn strictly rejects whitespace (spaces, tabs, newlines) in target names, source paths, include directories, compiler flags, and custom command outputs. Any whitespace triggers a clear diagnostic error:

  thorn: error: target name 'my app' contains whitespace
  

• Portability: All source paths within build.thorn should be relative to the project root directory.

System & Graph Limits

The graph model allocates fixed limits to ensure fast, deterministic operation without unbounded heap fragmentation:

• Maximum targets per project: 64
• Maximum sources per target: 256
• Maximum includes per target: 64
• Maximum cflags per target: 64
• Maximum ldflags per target: 64
• Maximum custom commands: 128
• Maximum order dependencies: 64

Exceeding these limits produces a descriptive diagnostic error at configuration time.

Design Philosophy

• No Implicit Globbing: Sources must be explicitly enumerated in build.thorn to prevent non-deterministic build ordering and missing dependencies.
• Strict Dependencies: All order dependencies must be explicitly declared using engine.add_order_dep().
• Minimal Dependencies: The Thorn binary relies only on standard POSIX C99 and the embedded Pith frontend/runtime.