multi: update to fn v2

lnwallet/aux_leaf_store.go

@@ -5,7 +5,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"

lnwallet/aux_resolutions.go

@@ -4,7 +4,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/tlv"

lnwallet/aux_signer.go

@@ -2,7 +2,7 @@ package lnwallet
 
 import (
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"

lnwallet/btcwallet/btcwallet.go

@@ -27,7 +27,7 @@ import (
 	"github.com/btcsuite/btcwallet/wtxmgr"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/blockcache"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/kvdb"

lnwallet/chainfee/filtermanager.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/rpcclient"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 )
 
 const (

lnwallet/chancloser/aux_closer.go

@@ -4,7 +4,7 @@ import (
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/tlv"

lnwallet/chancloser/chancloser.go

@@ -12,7 +12,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/labels"

lnwallet/chancloser/chancloser_test.go

@@ -14,7 +14,7 @@ import (
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntypes"

lnwallet/chancloser/interface.go

@@ -6,7 +6,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet"

lnwallet/chanfunding/canned_assembler.go

@@ -8,7 +8,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 )

lnwallet/chanfunding/interface.go

@@ -8,7 +8,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/btcsuite/btcwallet/wtxmgr"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 )
 

lnwallet/chanfunding/psbt_assembler.go

@@ -13,7 +13,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 )

lnwallet/channel.go

@@ -25,7 +25,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
@@ -600,7 +600,7 @@ func (lc *LightningChannel) extractPayDescs(feeRate chainfee.SatPerKWeight,
 
 		htlc := htlc
 
-		auxLeaf := fn.ChainOption(
+		auxLeaf := fn.FlatMapOption(
 			func(l CommitAuxLeaves) input.AuxTapLeaf {
 				leaves := l.OutgoingHtlcLeaves
 				if htlc.Incoming {
@@ -1106,7 +1106,7 @@ func (lc *LightningChannel) logUpdateToPayDesc(logUpdate *channeldb.LogUpdate,
 			feeRate, wireMsg.Amount.ToSatoshis(), remoteDustLimit,
 		)
 		if !isDustRemote {
-			auxLeaf := fn.ChainOption(
+			auxLeaf := fn.FlatMapOption(
 				func(l CommitAuxLeaves) input.AuxTapLeaf {
 					leaves := l.OutgoingHtlcLeaves
 					return leaves[pd.HtlcIndex].AuxTapLeaf
@@ -2088,7 +2088,7 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
 
 	// Since it is the remote breach we are reconstructing, the output
 	// going to us will be a to-remote script with our local params.
-	remoteAuxLeaf := fn.ChainOption(
+	remoteAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.RemoteAuxLeaf
 		},
@@ -2102,7 +2102,7 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
 		return nil, err
 	}
 
-	localAuxLeaf := fn.ChainOption(
+	localAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.LocalAuxLeaf
 		},
@@ -2229,7 +2229,7 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		br.LocalResolutionBlob = resolveBlob.Option()
+		br.LocalResolutionBlob = resolveBlob.OkToSome()
 	}
 
 	// Similarly, if their balance exceeds the remote party's dust limit,
@@ -2308,7 +2308,7 @@ func NewBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		br.RemoteResolutionBlob = resolveBlob.Option()
+		br.RemoteResolutionBlob = resolveBlob.OkToSome()
 	}
 
 	// Finally, with all the necessary data constructed, we can pad the
@@ -2338,7 +2338,7 @@ func createHtlcRetribution(chanState *channeldb.OpenChannel,
 	// We'll generate the original second level witness script now, as
 	// we'll need it if we're revoking an HTLC output on the remote
 	// commitment transaction, and *they* go to the second level.
-	secondLevelAuxLeaf := fn.ChainOption(
+	secondLevelAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) fn.Option[input.AuxTapLeaf] {
 			return fn.MapOption(func(val uint16) input.AuxTapLeaf {
 				idx := input.HtlcIndex(val)
@@ -2366,7 +2366,7 @@ func createHtlcRetribution(chanState *channeldb.OpenChannel,
 	// HTLC script. Otherwise, is this was an outgoing HTLC that we sent,
 	// then from the PoV of the remote commitment state, they're the
 	// receiver of this HTLC.
-	htlcLeaf := fn.ChainOption(
+	htlcLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) fn.Option[input.AuxTapLeaf] {
 			return fn.MapOption(func(val uint16) input.AuxTapLeaf {
 				idx := input.HtlcIndex(val)
@@ -2693,13 +2693,13 @@ type HtlcView struct {
 // AuxOurUpdates returns the outgoing HTLCs as a read-only copy of
 // AuxHtlcDescriptors.
 func (v *HtlcView) AuxOurUpdates() []AuxHtlcDescriptor {
-	return fn.Map(newAuxHtlcDescriptor, v.Updates.Local)
+	return fn.Map(v.Updates.Local, newAuxHtlcDescriptor)
 }
 
 // AuxTheirUpdates returns the incoming HTLCs as a read-only copy of
 // AuxHtlcDescriptors.
 func (v *HtlcView) AuxTheirUpdates() []AuxHtlcDescriptor {
-	return fn.Map(newAuxHtlcDescriptor, v.Updates.Remote)
+	return fn.Map(v.Updates.Remote, newAuxHtlcDescriptor)
 }
 
 // fetchHTLCView returns all the candidate HTLC updates which should be
@@ -2917,9 +2917,9 @@ func (lc *LightningChannel) evaluateHTLCView(view *HtlcView,
 	// The fee rate of our view is always the last UpdateFee message from
 	// the channel's OpeningParty.
 	openerUpdates := view.Updates.GetForParty(lc.channelState.Initiator())
-	feeUpdates := fn.Filter(func(u *paymentDescriptor) bool {
+	feeUpdates := fn.Filter(openerUpdates, func(u *paymentDescriptor) bool {
 		return u.EntryType == FeeUpdate
-	}, openerUpdates)
+	})
 	lastFeeUpdate := fn.Last(feeUpdates)
 	lastFeeUpdate.WhenSome(func(pd *paymentDescriptor) {
 		newView.FeePerKw = chainfee.SatPerKWeight(
@@ -2942,14 +2942,17 @@ func (lc *LightningChannel) evaluateHTLCView(view *HtlcView,
 	for _, party := range parties {
 		// First we run through non-add entries in both logs,
 		// populating the skip sets.
-		resolutions := fn.Filter(func(pd *paymentDescriptor) bool {
-			switch pd.EntryType {
-			case Settle, Fail, MalformedFail:
-				return true
-			default:
-				return false
-			}
-		}, view.Updates.GetForParty(party))
+		resolutions := fn.Filter(
+			view.Updates.GetForParty(party),
+			func(pd *paymentDescriptor) bool {
+				switch pd.EntryType {
+				case Settle, Fail, MalformedFail:
+					return true
+				default:
+					return false
+				}
+			},
+		)
 
 		for _, entry := range resolutions {
 			addEntry, err := lc.fetchParent(
@@ -3002,10 +3005,16 @@ func (lc *LightningChannel) evaluateHTLCView(view *HtlcView,
 	// settled HTLCs, and debiting the chain state balance due to any newly
 	// added HTLCs.
 	for _, party := range parties {
-		liveAdds := fn.Filter(func(pd *paymentDescriptor) bool {
-			return pd.EntryType == Add &&
-				!skip.GetForParty(party).Contains(pd.HtlcIndex)
-		}, view.Updates.GetForParty(party))
+		liveAdds := fn.Filter(
+			view.Updates.GetForParty(party),
+			func(pd *paymentDescriptor) bool {
+				isAdd := pd.EntryType == Add
+				shouldSkip := skip.GetForParty(party).
+					Contains(pd.HtlcIndex)
+
+				return isAdd && !shouldSkip
+			},
+		)
 
 		for _, entry := range liveAdds {
 			// Skip the entries that have already had their add
@@ -3063,7 +3072,7 @@ func (lc *LightningChannel) evaluateHTLCView(view *HtlcView,
 	uncommittedUpdates := lntypes.MapDual(
 		view.Updates,
 		func(us []*paymentDescriptor) []*paymentDescriptor {
-			return fn.Filter(isUncommitted, us)
+			return fn.Filter(us, isUncommitted)
 		},
 	)
 
@@ -3189,7 +3198,7 @@ func genRemoteHtlcSigJobs(keyRing *CommitmentKeyRing,
 		htlcFee := HtlcTimeoutFee(chanType, feePerKw)
 		outputAmt := htlc.Amount.ToSatoshis() - htlcFee
 
-		auxLeaf := fn.ChainOption(
+		auxLeaf := fn.FlatMapOption(
 			func(l CommitAuxLeaves) input.AuxTapLeaf {
 				leaves := l.IncomingHtlcLeaves
 				return leaves[htlc.HtlcIndex].SecondLevelLeaf
@@ -3270,7 +3279,7 @@ func genRemoteHtlcSigJobs(keyRing *CommitmentKeyRing,
 		htlcFee := HtlcSuccessFee(chanType, feePerKw)
 		outputAmt := htlc.Amount.ToSatoshis() - htlcFee
 
-		auxLeaf := fn.ChainOption(
+		auxLeaf := fn.FlatMapOption(
 			func(l CommitAuxLeaves) input.AuxTapLeaf {
 				leaves := l.OutgoingHtlcLeaves
 				return leaves[htlc.HtlcIndex].SecondLevelLeaf
@@ -4802,7 +4811,7 @@ func genHtlcSigValidationJobs(chanState *channeldb.OpenChannel,
 				htlcFee := HtlcSuccessFee(chanType, feePerKw)
 				outputAmt := htlc.Amount.ToSatoshis() - htlcFee
 
-				auxLeaf := fn.ChainOption(func(
+				auxLeaf := fn.FlatMapOption(func(
 					l CommitAuxLeaves) input.AuxTapLeaf {
 
 					leaves := l.IncomingHtlcLeaves
@@ -4895,7 +4904,7 @@ func genHtlcSigValidationJobs(chanState *channeldb.OpenChannel,
 				htlcFee := HtlcTimeoutFee(chanType, feePerKw)
 				outputAmt := htlc.Amount.ToSatoshis() - htlcFee
 
-				auxLeaf := fn.ChainOption(func(
+				auxLeaf := fn.FlatMapOption(func(
 					l CommitAuxLeaves) input.AuxTapLeaf {
 
 					leaves := l.OutgoingHtlcLeaves
@@ -6766,7 +6775,7 @@ func NewUnilateralCloseSummary(chanState *channeldb.OpenChannel, //nolint:funlen
 	// Before we can generate the proper sign descriptor, we'll need to
 	// locate the output index of our non-delayed output on the commitment
 	// transaction.
-	remoteAuxLeaf := fn.ChainOption(
+	remoteAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.RemoteAuxLeaf
 		},
@@ -6870,7 +6879,7 @@ func NewUnilateralCloseSummary(chanState *channeldb.OpenChannel, //nolint:funlen
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		commitResolution.ResolutionBlob = resolveBlob.Option()
+		commitResolution.ResolutionBlob = resolveBlob.OkToSome()
 	}
 
 	closeSummary := channeldb.ChannelCloseSummary{
@@ -7059,7 +7068,7 @@ func newOutgoingHtlcResolution(signer input.Signer,
 
 	// First, we'll re-generate the script used to send the HTLC to the
 	// remote party within their commitment transaction.
-	auxLeaf := fn.ChainOption(func(l CommitAuxLeaves) input.AuxTapLeaf {
+	auxLeaf := fn.FlatMapOption(func(l CommitAuxLeaves) input.AuxTapLeaf {
 		return l.OutgoingHtlcLeaves[htlc.HtlcIndex].AuxTapLeaf
 	})(auxLeaves)
 	htlcScriptInfo, err := genHtlcScript(
@@ -7149,7 +7158,7 @@ func newOutgoingHtlcResolution(signer input.Signer,
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		resolutionBlob := resolveRes.Option()
+		resolutionBlob := resolveRes.OkToSome()
 
 		return &OutgoingHtlcResolution{
 			Expiry:         htlc.RefundTimeout,
@@ -7171,7 +7180,7 @@ func newOutgoingHtlcResolution(signer input.Signer,
 
 	// With the fee calculated, re-construct the second level timeout
 	// transaction.
-	secondLevelAuxLeaf := fn.ChainOption(
+	secondLevelAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			leaves := l.OutgoingHtlcLeaves
 			return leaves[htlc.HtlcIndex].SecondLevelLeaf
@@ -7366,7 +7375,7 @@ func newOutgoingHtlcResolution(signer input.Signer,
 	if err := resolveRes.Err(); err != nil {
 		return nil, fmt.Errorf("unable to aux resolve: %w", err)
 	}
-	resolutionBlob := resolveRes.Option()
+	resolutionBlob := resolveRes.OkToSome()
 
 	return &OutgoingHtlcResolution{
 		Expiry:          htlc.RefundTimeout,
@@ -7406,7 +7415,7 @@ func newIncomingHtlcResolution(signer input.Signer,
 
 	// First, we'll re-generate the script the remote party used to
 	// send the HTLC to us in their commitment transaction.
-	auxLeaf := fn.ChainOption(func(l CommitAuxLeaves) input.AuxTapLeaf {
+	auxLeaf := fn.FlatMapOption(func(l CommitAuxLeaves) input.AuxTapLeaf {
 		return l.IncomingHtlcLeaves[htlc.HtlcIndex].AuxTapLeaf
 	})(auxLeaves)
 	scriptInfo, err := genHtlcScript(
@@ -7497,7 +7506,7 @@ func newIncomingHtlcResolution(signer input.Signer,
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		resolutionBlob := resolveRes.Option()
+		resolutionBlob := resolveRes.OkToSome()
 
 		return &IncomingHtlcResolution{
 			ClaimOutpoint:  op,
@@ -7507,7 +7516,7 @@ func newIncomingHtlcResolution(signer input.Signer,
 		}, nil
 	}
 
-	secondLevelAuxLeaf := fn.ChainOption(
+	secondLevelAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			leaves := l.IncomingHtlcLeaves
 			return leaves[htlc.HtlcIndex].SecondLevelLeaf
@@ -7707,7 +7716,7 @@ func newIncomingHtlcResolution(signer input.Signer,
 		return nil, fmt.Errorf("unable to aux resolve: %w", err)
 	}
 
-	resolutionBlob := resolveRes.Option()
+	resolutionBlob := resolveRes.OkToSome()
 
 	return &IncomingHtlcResolution{
 		SignedSuccessTx: successTx,
@@ -8011,7 +8020,7 @@ func NewLocalForceCloseSummary(chanState *channeldb.OpenChannel,
 		leaseExpiry = chanState.ThawHeight
 	}
 
-	localAuxLeaf := fn.ChainOption(
+	localAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.LocalAuxLeaf
 		},
@@ -8126,7 +8135,7 @@ func NewLocalForceCloseSummary(chanState *channeldb.OpenChannel,
 			return nil, fmt.Errorf("unable to aux resolve: %w", err)
 		}
 
-		commitResolution.ResolutionBlob = resolveBlob.Option()
+		commitResolution.ResolutionBlob = resolveBlob.OkToSome()
 	}
 
 	// Once the delay output has been found (if it exists), then we'll also

lnwallet/channel_test.go

@@ -25,7 +25,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
@@ -730,9 +730,12 @@ func TestCommitHTLCSigCustomRecordSize(t *testing.T) {
 
 		// Replace the default PackSigs implementation to return a
 		// large custom records blob.
-		mockSigner.ExpectedCalls = fn.Filter(func(c *mock.Call) bool {
-			return c.Method != "PackSigs"
-		}, mockSigner.ExpectedCalls)
+		mockSigner.ExpectedCalls = fn.Filter(
+			mockSigner.ExpectedCalls,
+			func(c *mock.Call) bool {
+				return c.Method != "PackSigs"
+			},
+		)
 		mockSigner.On("PackSigs", mock.Anything).
 			Return(fn.Ok(fn.Some(largeBlob)))
 	})

lnwallet/commitment.go

@@ -11,7 +11,7 @@ import (
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
@@ -836,7 +836,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
 			continue
 		}
 
-		auxLeaf := fn.ChainOption(
+		auxLeaf := fn.FlatMapOption(
 			func(leaves input.HtlcAuxLeaves) input.AuxTapLeaf {
 				return leaves[htlc.HtlcIndex].AuxTapLeaf
 			},
@@ -864,7 +864,7 @@ func (cb *CommitmentBuilder) createUnsignedCommitmentTx(ourBalance,
 			continue
 		}
 
-		auxLeaf := fn.ChainOption(
+		auxLeaf := fn.FlatMapOption(
 			func(leaves input.HtlcAuxLeaves) input.AuxTapLeaf {
 				return leaves[htlc.HtlcIndex].AuxTapLeaf
 			},
@@ -1323,7 +1323,7 @@ func findOutputIndexesFromRemote(revocationPreimage *chainhash.Hash,
 
 	// Compute the to_local script. From our PoV, when facing a remote
 	// commitment, the to_local output belongs to them.
-	localAuxLeaf := fn.ChainOption(
+	localAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.LocalAuxLeaf
 		},
@@ -1338,7 +1338,7 @@ func findOutputIndexesFromRemote(revocationPreimage *chainhash.Hash,
 
 	// Compute the to_remote script. From our PoV, when facing a remote
 	// commitment, the to_remote output belongs to us.
-	remoteAuxLeaf := fn.ChainOption(
+	remoteAuxLeaf := fn.FlatMapOption(
 		func(l CommitAuxLeaves) input.AuxTapLeaf {
 			return l.RemoteAuxLeaf
 		},

lnwallet/commitment_chain.go

@@ -1,7 +1,7 @@
 package lnwallet
 
 import (
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 )
 
 // commitmentChain represents a chain of unrevoked commitments. The tail of the

lnwallet/config.go

@@ -5,7 +5,7 @@ import (
 	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"

lnwallet/interface.go

@@ -19,7 +19,7 @@ import (
 	base "github.com/btcsuite/btcwallet/wallet"
 	"github.com/btcsuite/btcwallet/wallet/txauthor"
 	"github.com/btcsuite/btcwallet/wtxmgr"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/lnwallet/chanvalidate"

lnwallet/mock.go

@@ -18,7 +18,7 @@ import (
 	"github.com/btcsuite/btcwallet/wtxmgr"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/tlv"

lnwallet/musig_session.go

@@ -11,7 +11,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnwire"

lnwallet/reservation.go

@@ -12,7 +12,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntypes"

lnwallet/rpcwallet/rpcwallet.go

@@ -22,7 +22,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcwallet/waddrmgr"
 	basewallet "github.com/btcsuite/btcwallet/wallet"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lncfg"

lnwallet/test/test_interface.go

@@ -34,7 +34,7 @@ import (
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/chainntnfs/btcdnotify"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/kvdb"

lnwallet/test_utils.go

@@ -16,7 +16,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntypes"

lnwallet/transactions_test.go

@@ -21,7 +21,7 @@ import (
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntypes"

lnwallet/update_log.go

@@ -1,7 +1,7 @@
 package lnwallet
 
 import (
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 )
 
 // updateLog is an append-only log that stores updates to a node's commitment

lnwallet/wallet.go

@@ -23,7 +23,7 @@ import (
 	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb"
-	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lntypes"