Comments addressed

beacon_chain/beacon_chain_db.nim

@@ -18,11 +18,14 @@ type
 func subkey(kind: DbKeyKind): array[1, byte] =
   result[0] = byte ord(kind)
 
-func subkey[T](kind: DbKeyKind, key: T): auto =
-  var res: array[sizeof(T) + 1, byte]
-  res[0] = byte ord(kind)
-  copyMem(addr res[1], unsafeAddr key, sizeof(key))
-  return res
+func subkey[N: static int](kind: DbKeyKind, key: array[N, byte]):
+    array[N + 1, byte] =
+  result[0] = byte ord(kind)
+  result[1 .. ^1] = key
+
+func subkey(kind: DbKeyKind, key: uint64): array[sizeof(key) + 1, byte] =
+  result[0] = byte ord(kind)
+  copyMem(addr result[1], unsafeAddr key, sizeof(key))
 
 func subkey(kind: type BeaconState, key: Eth2Digest): auto =
   subkey(kHashToState, key.data)

beacon_chain/spec/crypto.nim

@@ -133,15 +133,13 @@ proc append*(writer: var RlpWriter, value: ValidatorPubKey) =
   writer.append value.getBytes()
 
 proc read*(rlp: var Rlp, T: type ValidatorPubKey): T {.inline.} =
-  let r = rlp.read(seq[byte])
-  if not init(result, r):
-    raise newException(Exception, "Could not init ValidatorPubKey from bytes")
+  result = ValidatorPubKey.init(rlp.toBytes.toOpenArray)
+  rlp.skipElem()
 
 proc append*(writer: var RlpWriter, value: ValidatorSig) =
   writer.append value.getBytes()
 
 proc read*(rlp: var Rlp, T: type ValidatorSig): T {.inline.} =
-  let r = rlp.read(seq[byte])
-  if not init(result, r):
-    raise newException(Exception, "Could not init ValidatorSig from bytes")
+  result = ValidatorSig.init(rlp.toBytes.toOpenArray)
+  rlp.skipElem()