Are you thinking of this, formerly known as Lumen? https://github.com/GetFirefly/firefly https://github.com/GetFirefly/firefly AFAIK it's been mothballed and

Are you thinking of this, formerly known as Lumen? https://github.com/GetFirefly/firefly https://github.com/GetFirefly/firefly AFAIK it's been mothballed and one of the major contributors seems to have left the BEAM ecosystem altogether. They're doing Ethereum-ish smart-contract-ish stuff now. The other top contributor looks to have pulled way back from OSS dev of any kind.