Documentation

data T a Source

Handle of a transactional variable

Instances

Read (T a)
Show (T a)

init :: (Types a, Read a, Show a) => String -> a -> TCGI b (T a)Source

Attempt to create a new tv n and set its initial value. Returns handle to the variable. If the variable already exists, then just returns the handle.

create :: (Read a, Show a, Types a) => a -> TCGI b (T a)Source

Create a fresh transactional variable with an initial value and return its handle. Performs a physical write to ensure that the variable's name is unique. Locks the transaction directory during the write operation.

remove :: Types a => T a -> TCGI b ()Source

Remove a transactional variable. Subsequent read accesses to this variable will make the transaction fail. May throw an exception if the variable is not present.

get :: (Read a, Show a) => T a -> TCGI b aSource

Read transactional variable through a typed handle.

set :: (Read a, Show a) => T a -> a -> TCGI b ()Source

Write to a transactional variable through typed handle. Only affects the log, no physical write happens. Checks physically for existence of the variable (but tries the log first). Raises exception if it does not exist.

with :: (WithMonad cgi, Read result, Show result) => result -> (result -> cgi ()) -> (Control (TCGI result) result -> TCGI result ()) -> cgi ()Source

data Control cgi result Source

Constructors

Control
Fields abandon :: result -> cgi () abandon with result (rollback) setFail :: result -> cgi () set result on failure setCommit :: result -> cgi () set result on successful commit

data TCGI b a Source

Type of a CGI action in a transactional scope with a result variable of type a.

Instances

Monad (TCGI b)
CGIMonad (TCGI b)
WithMonad (TCGI x)