Ethereum smart contracts in Nim

Disclaimer: WIP

This is a sample of how building eWASM contracts in Nim is possible. Requirements:

• clang 7.0 or later with WebAssembly support. Most likely has to be built manually.
• 32bit version of libc. On linuxes it is usually provided by the package manager.
• wasm2wat and wat2wasm from wabt (WebAssembly binary toolkit). They need to be in the PATH.
• [optional] wasm-gc optimizer

Compiling examples

export WASM_LLVM_BIN=/path/to/llvm/bin/folder
nimble examples

Troubleshooting

• Emscripten doesn't work! It is not expected to. Use clang with wasm target enabled.
• clang is difficult to build. No, it's easy. Follow these steps:

tag=release_70
INSTALL_PREFIX=$(pwd)/llvm-wasm
git clone --depth 1 --branch $tag https://github.com/llvm-mirror/llvm.git
cd llvm/tools
git clone --depth 1 --branch $tag https://github.com/llvm-mirror/clang
git clone --depth 1 --branch $tag https://github.com/llvm-mirror/lld
cd ..
mkdir build
cd build
cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$INSTALL_PREFIX -DLLVM_TARGETS_TO_BUILD= -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=WebAssembly ..
make -j 4 install

• C compiler errors: headers not found. Make sure you have 32bit libc installed and visible to your clang.

License

Licensed under one of the following:

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license: LICENSE-MIT or http://opensource.org/licenses/MIT