How to use the ABI of a Reach program from outside Reach?

[DanBurton]

Discord user russfustino asks:

Can someone point me to an ABI sample? One where Reach creates the spec for the contract and can be used by any application including an Algorand SDK solution? Analogus to contract.py in https://github.com/algorand-devrel/demo-avm1.1

[DanBurton]

examples/remote-rsh shows how to it within Reach.
https://github.com/reach-sh/reach-lang/blob/master/examples/remote-rsh/index.rsh

When you ask for an example "where Reach creates the spec for the contract", the way you create the ABI spec is through Reach's API and View features.

Any APIs you create in Reach are compliant with the Algorand ABI.
https://docs.reach.sh/rsh/appinit/#ref-programs-appinit-api

When you create a remote(addr, interface) object in Reach, it uses the ABI according to the function names and types as specified in interface. This works whether the remote contract is a Reach contract or not, because Reach uses the same ABI standards as everyone else to implement its API functionality.

Note that Views are also compliant with the ABI. Views have no effect on the contract but are a way that other contracts can extract information from a Reach program via the ABI.

We don't have an example of a non-Reach program using a Reach program's API via the ABI, but once you understand that Reach's APIs and Views are how the contract's ABI is specified, then you should be able to interact with a Reach contract's ABI in the same way you'd do it for any other non-Reach contract.

To extract the ABI for a given Reach contract, you can use ctc.getABI()
https://docs.reach.sh/frontend/#js_ctc.getABI

const acc = await reach.createAccount();
const ctc = acc.contract(bin);
console.log(ctc.getABI());