# Modules, imports, packages ## Single-file mode A `.cplus` file compiled with `cpc file.cplus -o bin` has no imports; only [intrinsics](/docs/intrinsics) are available. ## Project mode Every import declares **where** the module comes from. Bare paths are rejected: the resolver makes you say "local" or "vendored". ```cplus // Local file at src/math.cplus import "./math" as math; math::area(2, 3); // Vendored package — the path's first segment is the dep name from Cplus.toml import "stdlib/io" as io; io::println("hi"); ``` - **Local** imports start with `./`, resolved relative to the current file. - **Vendored** imports have a first segment matching a `[dependencies]` entry, resolved from `vendor//src/.cplus`. The alias is **mandatory**: `import "X" as Y;`, then you call into the module as `Y::thing(...)`. There are no glob imports and no `use`. This is part of what keeps a file legible: every external name is traceable to the line that imported it. ## `pub` for cross-file visibility By default everything is module-private. `pub` exports. ```cplus pub fn answer() -> i32 { return 42; } pub struct Public { pub field: i32 } pub enum Color { Red, Green, Blue } ``` ## `Cplus.toml` ```toml [package] name = "myproj" version = "0.0.1" edition = "2026" [[bin]] name = "myproj" path = "src/main.cplus" [dependencies] stdlib = "*" ``` The standard library is consumed like any other vendored package. This is the same model every package uses; see [Packages](/docs/packages) for the full catalog and how dependency resolution walks the `vendor/` checkout. ## `[link]` — library search paths When a project links a native library that lives outside the linker's default search path — CUDA's `lib64`, a custom OpenBLAS prefix — list the directories in a `[link]` table: ```toml [link] search-paths = ["/usr/local/cuda/lib64", "/opt/openblas/lib"] ``` Each entry becomes both `-L` at link time and `-Wl,-rpath,` at run time, so the library resolves when you build *and* when you run, with no `LD_LIBRARY_PATH`. Relative entries resolve against the manifest directory. This is what lets the [GPU & numerics](/docs/gpu-numerics) packages link their vendor SDKs cleanly.