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diff --git a/doc/manual.tex b/doc/manual.tex index 052249ce..a5b9c44e 100644 --- a/doc/manual.tex +++ b/doc/manual.tex @@ -1389,6 +1389,8 @@ $$\begin{array}{l} \hspace{.1in} \to \mt{monad} \; \mt{m} \end{array}$$ +The Ur/Web compiler provides syntactic sugar for monads, similar to Haskell's \cd{do} notation. An expression $x \leftarrow e_1; e_2$ is desugarded to $\mt{bind} \; e_1 \; (\lambda x \Rightarrow e_2)$, and an expression $e_1; e_2$ is desugared to $\mt{bind} \; e_1 \; (\lambda () \Rightarrow e_2)$. + \subsection{Transactions} Ur is a pure language; we use Haskell's trick to support controlled side effects. The standard library defines a monad $\mt{transaction}$, meant to stand for actions that may be undone cleanly. By design, no other kinds of actions are supported. |