Etherpc

Idiomatic Ethereum/Infura JSON-RPC client for Crystal, supporting WebSockets and subscriptions.

Below is the aspirational API and doesn't work yet.

client = Etherpc::WebSocketClient.new "wss://mainnet.infura.io/ws/v3/#{PROJECT_ID}"

price = client.gas_price
puts "Gas costs #{price.to_gwei} gwei"

token = Etherpc::Contracts::Erc20 "0x9f8F72aA9304c8B593d555F12eF6589cC3A579A2", client
balance = token.balance_of "0xBE0eB53F46cd790Cd13851d5EFf43D12404d33E8"
puts "You have #{balance} #{token.symbol}"

number_of_messages = 0
client.new_heads do |subscription|
    subscription.each_event do |event|
        number_of_messages += 1
        subscription.cancel if number_of_messages == 10
    end
end

Examples

Examples can be found in the examples folder.

To run them, do:

$ crystal run examples/basic.cr -- [endpoint] [address] [token address]

Roadmap

High-priority items that need to be done before v0.1:

• Refactor subscription API
• HTTP transport
• Helper factories to create clients with a given transport
• Support for most of the geth/Infura RPC calls
• Thorough specs
• Error handling

Longer term:

• Contract ABI support
• Use mappings for deserialization
• Move common internal functions into util.cr
• to_ether/to_gwei/to_bloom_filter utility functions
• Infura authenticated endpoint helpers
• parity_subscribe support
• Possibly high-level account/wallet API