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EXPERIENCES.md

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The following code does not type check, as GHC cannot see that sync1 and sync2 use sender1, sender2, receiver1, and receiver2 are used linearly.

newSyncOnce :: Linear.IO (SyncOnce, SyncOnce)
newSyncOnce =
  let (>>=) = (Linear.>>=) in do
    (sender1, receiver1) <- new
    (sender2, receiver2) <- new
    let sync1 = SyncOnce (sender1, receiver2)
    let sync2 = SyncOnce (sender2, receiver1)
    Linear.return (sync1, sync2)

The following code, inlining these definition, does type check, which leads me to believe there is something fundamental about let bindings which are not inspected by GHC for usage:

newSyncOnce :: Linear.IO (SyncOnce, SyncOnce)
newSyncOnce =
  let (>>=) = (Linear.>>=) in do
    (sender1, receiver1) <- new
    (sender2, receiver2) <- new
    Linear.return
        ( SyncOnce (sender1, receiver2)
        , SyncOnce (sender2, receiver1)
        )