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Calculator end-to-end

Goal

Take the in-tree samples/calculator IDL, generate bindings for every target, build the cdylib, and run the calculator from a real consumer (C, Node.js, Swift, then optionally Android and WASM). By the end you will have produced bindings, executed them on at least one host, and seen the same Rust add(a, b) answer come back through three different runtimes.

Prerequisites

  • Rust toolchain (stable channel) with cargo on PATH.
  • The WeaveFFI CLI (cargo install weaveffi-cli or cargo run -p weaveffi-cli -- if you are working in the repo).
  • macOS or Linux for the C/Node/Swift steps; Windows works for C and Node but the Swift step requires macOS.
  • For the optional Android and WASM steps:
    • Android Studio with the NDK installed.
    • rustup target add wasm32-unknown-unknown.

Step-by-step

1. Generate every target

weaveffi generate samples/calculator/calculator.yml -o generated

The output appears under generated/:

  • generated/c — C header and convenience C file
  • generated/swift — SwiftPM System Library (CWeaveFFI) and Swift wrapper (WeaveFFI)
  • generated/android — Kotlin wrapper, JNI shims, and Gradle skeleton
  • generated/node — N-API loader and .d.ts
  • generated/wasm — minimal WASM loader

2. Build the Rust sample

cargo build -p calculator

The cdylib lands in target/debug/:

  • macOS: libcalculator.dylib
  • Linux: libcalculator.so
  • Windows: calculator.dll

3. Run the C example

macOS:

cd examples/c
cc -I ../../generated/c main.c -L ../../target/debug -lcalculator -o c_example
DYLD_LIBRARY_PATH=../../target/debug ./c_example

Linux:

cd examples/c
cc -I ../../generated/c main.c -L ../../target/debug -lcalculator -o c_example
LD_LIBRARY_PATH=../../target/debug ./c_example

4. Run the Node example

macOS:

cp target/debug/libindex.dylib generated/node/index.node
cd examples/node
DYLD_LIBRARY_PATH=../../target/debug npm start

Linux:

cp target/debug/libindex.so generated/node/index.node
cd examples/node
LD_LIBRARY_PATH=../../target/debug npm start

5. Run the Swift example (macOS / Linux)

cargo build -p calculator
cd examples/swift
swiftc \
  -I ../../generated/swift/Sources/CWeaveFFI \
  -L ../../target/debug -lcalculator \
  -Xlinker -rpath -Xlinker ../../target/debug \
  Sources/App/main.swift -o .build/debug/App
DYLD_LIBRARY_PATH=../../target/debug .build/debug/App

On Linux replace DYLD_LIBRARY_PATH with LD_LIBRARY_PATH.

6. Optional: Android and WASM

  • Open generated/android in Android Studio and build the :weaveffi AAR. Combine with the steps in the Android tutorial.
  • For WASM, run cargo build --target wasm32-unknown-unknown --release and load the .wasm file with generated/wasm/weaveffi_wasm.js.

Verification

You should see the same calculator output from each consumer, e.g. 2 + 3 = 5. Concretely:

  • The C example prints 2 + 3 = 5 (or whatever expression examples/c/main.c exercises) without any weaveffi: error messages.
  • npm start exits with code 0 and prints the calculator results followed by the Done. banner.
  • The Swift binary launches, prints the same arithmetic, and exits cleanly.

If the host cannot find the cdylib, you will see dyld: Library not loaded (macOS) or error while loading shared libraries (Linux). Re-export DYLD_LIBRARY_PATH / LD_LIBRARY_PATH and rerun.

Cleanup

rm -rf generated/
cargo clean -p calculator
rm -rf examples/c/c_example examples/swift/.build

The generated/ directory is safe to delete and recreate; nothing else in the repository depends on its contents.

Next steps