Polkadot Storage

Blockchains that are built with Substrate expose a remote procedure call (RPC) server that can be used to query runtime storage. In Haskell Web3 the standard Web3 provider could be used.

Lets try to query Polkadot storage with runWeb3' function using ghci.

> import Network.Web3.Provider
> import Network.Polkadot
> runWeb3' (WsProvider "127.0.0.1" 9944) (query "timestamp" "now" [] :: Web3 (Either String Moment))
Right (Right 1610689972001)

The query function arguments is section (or module), method and list of arguments (for maps and double maps).

query :: (JsonRpc m, Decode a) => Text -> Text -> [Argument] -> m a

Where a type should be SCALE decodable.

Note

More usage details available in Polkadot example app.