tricu

An interpreted language for exploring Tree Calculus
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sourceModuleAtomicIO.tri (986B)

      1 !import "io" !Local
      2 !import "prelude" !Local
      3 path = "__PATH__"
      4 check condition = pure (if condition (ok t t) (err "atomic IO mismatch" t))
      5 main = io (onResult_ (do onOk_
      6   first <- writeBytesIfAbsent path [(0) (255)]
      7   _ <- check first
      8   second <- writeBytesIfAbsent path [(1)]
      9   _ <- check (not? second)
     10   before <- readFile path
     11   _ <- check (equal? before [(0) (255)])
     12   _ <- atomicWriteBytes path [(7)]
     13   after <- readFile path
     14   _ <- check (equal? after [(7)])
     15   _ <- onResult_ (sha256Hex [(256)])
     16     (problem : pure (if (equal? problem "invalid bytes")
     17       (ok t t) (err "wrong invalid-bytes error" t)))
     18     (_ : pure (err "accepted invalid byte" t))
     19   _ <- onResult_ (readFile (append path ".missing"))
     20     (problem : pure (if (equal? problem "does not exist")
     21       (ok t t) (err "wrong missing-file error" t)))
     22     (_ : pure (err "accepted missing file" t))
     23   pure (ok t t))
     24   (problem : putStrLn (append "atomic-io-failed: " problem))
     25   (_ : putStrLn "atomic-io-ok"))
     26 main