• Move over all pallets using Currency to fungible traits:
  • Basic code switch over: pallets should provide a utility for cancelling a lock/reserve and instating a freeze/hold.
  • Staking pallet should use hold instead of lock.
  • Permissionless fee-free dispatchable in all pallets to move over.
  • Mark all Currency traits as deprecated.

Eventually, we will also want to deprecate and remove Balances dispatchables:

• Substitute all usages of Balances dispatchables with fungible API.
• Mark dispatchables as deprecated.
• Remove them (this can only be done once XCM execution from private accounts is safe and enabled).

Pallet migrations needed

Here's a list of pallets, turning this into a tracking issue of the migration process.

• CurrencyAdapter, as per Inconsistent Transferable Balance Calculation Logic #1833 Migrate fee payment from Currency to fungible #2292.
• ./frame/staking/src/pallet/mod.rs type Currency: LockableCurrency
• ./frame/assets/src/lib.rs @gilescope type Currency: ReservableCurrency<Self::AccountId>;
• ./frame/elections-phragmen/src/lib.rs type Currency: LockableCurrency<Self::AccountId, Moment = Self::BlockNumber> Pallet Elections Phragment migrates to use Fungibles trait #2011
• ./frame/election-provider-multi-phase/src/lib.rs type Currency: ReservableCurrency<Self::AccountId> + Currency<Self::AccountId>;
• ./frame/lottery/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Pallet Lottery migrate to Fungibles traits #1810
• Fungibles: migrate Democracy pallet #1861
• ./frame/treasury/src/lib.rs type Currency: Currency<Self::AccountId> + ReservableCurrency<Self::AccountId>; @juangirini
• ./frame/nicks/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactor pallet-state-trie-migration to fungible::* traits #1801
• ./frame/state-trie-migration/src/lib.rs type Currency: Currency<Self::AccountId>; Refactor pallet-state-trie-migration to fungible::* traits #1801
• ./frame/nfts/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactors pallet-nfts to use fungible traits  #1804
• ./frame/uniques/src/lib.rs @jsidorenko type Currency: ReservableCurrency<Self::AccountId>; Refactors pallet-uniques to use fungible traits #1866
• /frame/nis/src/lib.rs type Currency: FunInspect<Self::AccountId, Balance = Self::CurrencyBalance>
• ./frame/vesting/src/lib.rs type Currency: LockableCurrency<Self::AccountId>; pallet vesting / update to use fungible #1760
• ./frame/contracts/src/lib.rs @juangirini Contracts: migrate to fungible traits substrate#14020 type Currency: ReservableCurrency<Self::AccountId> // TODO: Move to fungible traits
• ./frame/identity/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; @juangirini Refactor pallet identity to fungibles #2822
• ./frame/scored-pool/src/lib.rs `type Currency: CurrencySelf::AccountId + ReservableCurrencySelf::AccountId; Scored Pool - Migrate to Fungible Trait #1834
• ./frame/fast-unstake/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; migrate pallet-fast-unstake to fungible::* trait family #1772
• ./frame/society/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactor society pallet to use fungible traits #1853
• ./frame/multisig/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Migrates pallet-multisig to Consideration #1782 -> to be revisited (probably w/o Considerations)
• ./frame/asset-rate/src/lib.rs type Currency: Inspect<Self::AccountId, Balance = Self::Balance>;
• ./frame/nomination-pools/src/lib.rs @Ank4n type Currency: Currency<Self::AccountId>;
• ./frame/alliance/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; pallet alliance / update to use fungible #1675
• ./frame/statement/src/lib.rs type Currency: Inspect<Self::AccountId>;
• ./frame/recovery/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; @juangirini Refactor pallet recovery to fungibles #1807
• ./frame/preimage/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; FRAME: General storage-usage system substrate#13666
• ./frame/conviction-voting/src/lib.rs type Currency: ReservableCurrency<Self::AccountId> Conviction pallet uses fungible trait #1821
• ./frame/proxy/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Use Consideration ticket for holding Proxy pallet deposits #1837 deprecated in favor of @sigurpol proxy: migrate from Currency to fungible traits #9560
• ./frame/indices/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactor indices pallet #1789
• ./frame/transaction-storage/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactor transaction storage pallet to use fungible traits #1800
• ./frame/referenda/src/lib.rs type Currency: ReservableCurrency<Self::AccountId>; Refactors referenda pallet to use fungible traits #1785
• bridges/modules/relayers/src/stake_adapter.rs Currency: NamedReservableCurrency<AccountId> (@bkontur working on it)
• bridges/bin/runtime-common/src/refund_relayer_extension.rs ReservableCurrency (@bkontur working on it)