acid-state

问题 I'm a newbie to Haskell, and wanted to try the acid-state library, but I get the following output when trying to install it: >cabal install acid-state Resolving dependencies... Configuring acid-state-0.7.5... Building acid-state-0.7.5... Preprocessing library acid-state-0.7.5... [ 1 of 15] Compiling Data.Acid.CRC ( src\Data\Acid\CRC.hs, dist\build\Data\Ac id\CRC.o ) [ 2 of 15] Compiling Paths_acid_state ( dist\build\autogen\Paths_acid_state.hs, dist\build\Paths_acid_state.o ) [ 3 of 15]

问题 I'm trying acid-state . The documentation states that Update st is an instance of MonadState st . I tried different things, but my compiler doesn't want to see that :( I tried the HelloWorld.hs from examples, but got the same issue: HelloWorld.hs:26:7: No instance for (MonadState HelloWorldState (Update HelloWorldState)) arising from a use of `put' Possible fix: add an instance declaration for (MonadState HelloWorldState (Update HelloWorldState)) In the expression: put (HelloWorldState

问题 I'm trying acid-state . The documentation states that Update st is an instance of MonadState st . I tried different things, but my compiler doesn't want to see that :( I tried the HelloWorld.hs from examples, but got the same issue: HelloWorld.hs:26:7: No instance for (MonadState HelloWorldState (Update HelloWorldState)) arising from a use of `put' Possible fix: add an instance declaration for (MonadState HelloWorldState (Update HelloWorldState)) In the expression: put (HelloWorldState

问题 I wanted to write a multi-statement transaction in server-side JavaScript in marklogic. What I wanted to achieve is, do an update transaction and then write a query statement which queries for the updated document and confirm that the update is visible within the transaction and finally do a rollback. By doing the rollback, I wanted to confirm that the update made within the transaction is not visible outside the transaction and it is visible within the transaction. I wrote a code both in