haddocks: added a note on resource allocation

typed-protocols-stateful/src/Network/TypedProtocol/Stateful/Peer.hs

@@ -67,7 +67,14 @@ import Network.TypedProtocol.Core as Core
 -- 'Network.TypedProtocol.Peer.Client' or 'Network.TypedProtocol.Peer.Server'
 -- pattern synonyms provide this evidence automatically.
 --
--- TODO:
+-- __NOTE__:
+-- one should not allocate resources within a `Peer` since there's no way to
+-- safely clean-up resources in case of an asynchronous exception.  The proper
+-- way to allocate resources is to call
+-- `Network.TypedProtocol.Stateful.Driver.runPeerWithDriver` within
+-- a `Control.Exception.bracket`.
+--
+-- __TODO__:
 -- We are not exposing pipelined version, since it is not possible to write
 -- a driver & proofs in a type safe which take into account the state when the
 -- peer type only tracks depth of pipelining rather than pipelined transitions.

typed-protocols/src/Network/TypedProtocol/Peer.hs

@@ -79,6 +79,13 @@ import           Network.TypedProtocol.Core as Core
 -- "Network.TypedProtocol.Peer.Client" supply this evidence for you, and hence
 -- are easier to use and let you avoid some kinds of type errors.
 --
+-- __NOTE__:
+-- one should not allocate resources within a `Peer` since there's no way to
+-- safely clean-up resources in case of an asynchronous exception.  The proper
+-- way to allocate resources is to call
+-- `Network.TypedProtocol.Driver.runPeerWithDriver` (or `runPeer`,
+-- `runPipelinedPeer`) within a `Control.Exception.bracket`.
+--
 type Peer :: forall ps
           -> PeerRole
           -> IsPipelined