úÎ Qœ non-portable experimentalmainland@eecs.harvard.eduNone.Atomically mutate the contents of a reference The 7 type class abstracts over the details of manipulating M references, allowing one to write code that uses references and can operate 2 in any monad that supports reference operations. Create a new reference Read the value of a reference !Write a new value to a reference #Mutate the contents of a reference !    !      !"#ref-tf-0.3.0.2Control.Monad.RefMonadAtomicRefatomicModifyRefMonadRefRefnewRefreadRefwriteRef modifyRef$fMonadAtomicRefWriterT$fMonadAtomicRefWriterT0$fMonadAtomicRefStateT$fMonadAtomicRefStateT0$fMonadAtomicRefReaderT$fMonadAtomicRefMaybeT$fMonadAtomicRefListT$fMonadAtomicRefIdentityT$fMonadAtomicRefErrorT$fMonadAtomicRefContT$fMonadAtomicRefSTM$fMonadAtomicRefIO$fMonadRefWriterT$fMonadRefWriterT0$fMonadRefStateT$fMonadRefStateT0$fMonadRefReaderT$fMonadRefMaybeT$fMonadRefListT$fMonadRefIdentityT$fMonadRefErrorT$fMonadRefContT $fMonadRefSTM $fMonadRefIO $fMonadRefST