cosmwasm-go

README

Overview

This is a demo for cosmwasm-go build, it is in alpha state, but it is compatible with CosmWasm 0.16.

This is currently in a private pre-release. This repo should only be shared with select developers who will work on improving it. When we are happy with the stability, we will publish this.

Features

The following areas have been tested, both in unit tests and in integration tests using go-cosmwasm to ensure compatibility. Please look at the hackatom contract for a good example with test coverage.

• Export instantiate, execute, query, migrate and return success response or errors
• Get and Set from persistent storage
• Canonicalize and Humanize addresses with the Api
• Query into the bank module (use querier)
• Efficiently parse json structs
• Simple API so you can focus on the business logic
• Easy setup and similar format for unit test and integration tests, to allow easy porting them.

The following areas have some code but have not been tested and likely buggy:

• Remove from storage
• Storage iterators
• Querying staking/wasm modules

These can be called, but will likely not function 100% and will require some debugging to get them working.

Caveats

Beyond the "likely buggy" Apis above, the following "features" are definitely not implemented:

• Support for Uint128 (parsing strings, dealing with large integers)
• Helper functions for creating messages or queries

JSON

We have a major fork of easyjson that removes all calls to reflect and net and fmt and encoding/json. It also removes all floats and parses numbers directly into ints.

We call it tinyjson. v0.8.x is the first version after forking (easyjson is at 0.7.x) and already working quite well.

It works like encoding/json, but uses code generation to create MarshalJSON and UnmarshalJSON methods on all structs when you run a generation stage. After that, you can simply call those methods on the structs to do all parsing.

It handles slices and pointers and all kinds of other things just like encoding/json. It automatically snake_cases's the variable names if you compile with snake_case, which saves some work in the structs. It turns []byte into base64 strings, and it properly escapes other strings.

A special feature is the custom emptyslice option, which you can add just like omitempty. With that, it means any slice of length 0 will serialize as [] rather than null (the default behavior). This avoids the need for most of the custom JSON marshallers that we just doing this.

Usage

We require docker installed and executable by the current user. This is used to compile the contracts to Wasm. You can code contracts and write unit test with only a normal Golang installation (requires 1.14+)

You can try the following top-level commands:

# Run unit tests on the standard library as well as `erc20` and `hackatom` contracts.
# Also compiles the contracts to wasm and runs integration tests
make test

# This will compile wasm binaries for all contracts and leave them in this directory
make examples

To try out a contract, either check out hackatom, running the tests and editing the code. Or start your own contract by going to the template directory and follow the instructions on how to get started.

Both of these support the following commands: make unit-test, make build, and make test.

Performance

Many people ask how these compare to the rust contracts. I have yet to do a detailed comparion, but now that we have two versions of the same hackatom contract, we can do a rough side-by-side analysis.

Once this is more or less feature-complete, we need to do a more detailed analysis. I assume contract size will be significantly larger when it has all the features we have in Rust.

The good:

The contract size is significantly lower than the Rust version, that is 97kB for the TinyGo version compared to 179kB for the Rust version. (There is a sha256 algorithm in the Rust version missing from the Go version, but that is only about 20Kb of the size)

The bad:

Before I switched to tinyjson, this used significantly more gas. Now, it seems to use about 1.5-2x more gas than the Rust contracts. And the compiled size is about 50% of the Rust size.

Development

This library is very experimental. If you want to try to build contracts or hack on the library itself, please check out DEVELOPMENT.md for more details.