The mutable cell is in the tail. A [TVar a] would be quite different. You can read about a very similar impl (based on MVars) in the original "Concurrent Haskell" paper (on my papers page) S | -----Original Message----- | From: Joel Reymont [mailto:joelr1@gmail.com] | Sent: 06 December 2005 11:28 | To: Simon Peyton-Jones | Cc: Haskell Cafe | Subject: TChan implementation: Why TVarList | | Simon, | | Why did you guys implement TChan on top of your own TVarList instead | of a regular list? | | -- | 'TChan' is an abstract type representing an unbounded FIFO channel. | data TChan a = TChan (TVar (TVarList a)) (TVar (TVarList a)) | | type TVarList a = TVar (TList a) | data TList a = TNil | TCons a (TVarList a) | | Thanks, Joel | | -- | http://wagerlabs.com/ | | | |