This project was born out of my quest to understand and build compilers.
There is a PDF in the root directory named WebAssembly.pdf. The implementation of the compiler is based on this guide. If you have not already you can go through it to understand the ABI.
The grammar for the language set is defined in ast/grammar.pest. I am using Parsing Expression Grammars (PEG) to parse the source into a token stream. The library being used is pest.rs
An AST is created from the token stream. This AST is optimized by a simple algorithm; if the value of the two children of a binary operation can be derived at compile time then execute the binary tree at compile time and return the resultant node. This saves time spent in running unnecessary instructions at runtime. Then using the ABI, this AST is compiled down to WASM byte code.
The source code for the parser, optimizer and ABI implementation is in src/parser.rs. There are some helper functions in src/functions.rs that help create abstractions over the WebAssembly constructs. A sample script showing an example of a working program written using the defined grammar is stored in source/index.wasl.