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diff --git a/presentations/servant-2016/slides.tex b/presentations/servant-2016/slides.tex new file mode 100644 index 000000000000..d5947eb9421a --- /dev/null +++ b/presentations/servant-2016/slides.tex @@ -0,0 +1,137 @@ +\documentclass[12pt]{beamer} +\usetheme{metropolis} +\usepackage{minted} + +\newenvironment{code}{\ttfamily}{\par} + +\title{servant} +\subtitle{Defining web APIs at the type-level} + +\begin{document} +\metroset{titleformat frame=smallcaps} +\setminted{fontsize=\scriptsize} + + +\maketitle + +\section{Introduction} + +\begin{frame}{Type-level DSLs?} + \begin{itemize} + \item (Uninhabited) types with attached ``meaning'' + \item The Expression Problem (Wadler 1998) + \item API representation and interpretation are separated + \item APIs become first-class citizens + \end{itemize} +\end{frame} + +\begin{frame}{Haskell extensions} + \begin{itemize} + \item TypeOperators + \item DataKinds + \item TypeFamilies + \end{itemize} +\end{frame} + +\begin{frame}[fragile]{A servant example} + \begin{minted}{haskell} + type PubAPI = "pubs" :> Get ’[JSON] [Pub] + :<|> "pubs" :> "tagged" + :> Capture "tag" Text + :> Get ’[JSON] [Pub] + \end{minted} +\end{frame} + +\begin{frame}[fragile]{Computed types} + \begin{minted}{haskell} + type TaggedPubs = "tagged" :> Capture "tag" Text :> ... + + taggedPubsHandler :: Server TaggedPubs + taggedPubsHandler tag = ... + \end{minted} +\end{frame} + +\begin{frame}[fragile]{Computed types} + \begin{minted}{haskell} + type TaggedPubs = "tagged" :> Capture "tag" Text :> ... + + taggedPubsHandler :: Server TaggedPubs + taggedPubsHandler tag = ... + + Server TaggedPubs ~ + Text -> EitherT ServantErr IO [Pub] + \end{minted} +\end{frame} + +\section{Interpretations} + +\begin{frame}{servant-server} + The one everyone is interested in! + + \begin{itemize} + \item Based on WAI, can run on warp + \item Interprets combinators with a simple \texttt{HasServer c} class + \item Easy to use! + \end{itemize} +\end{frame} + +\begin{frame}[fragile]{HasServer ...} + \begin{minted}{haskell} + instance (KnownSymbol path, HasServer sublayout) + => HasServer (path :> sublayout) where + type ServerT (path :> sublayout) m = ServerT sublayout m + + route ... + where + pathString = symbolVal (Proxy :: Proxy path) + \end{minted} +\end{frame} + +\begin{frame}[fragile]{Server example} + \begin{minted}{haskell} + type Echo = Capture "echo" Text :> Get ’[PlainText] Text + + echoAPI :: Proxy Echo + echoAPI = Proxy + + echoServer :: Server Echo + echoServer = return + \end{minted} +\end{frame} + +\begin{frame}{servant-client} + \begin{itemize} + \item Generates Haskell client functions for API + \item Same types as API specification: For RPC the whole ``web layer'' is abstracted away + \item Also easy to use! + \end{itemize} +\end{frame} + +\begin{frame}{servant-docs, servant-js ...} + Many other interpretations exist already, for example: + \begin{itemize} + \item Documentation generation + \item Foreign function export (e.g. Elm, JavaScript) + \item Mock-server generation + \end{itemize} +\end{frame} + +\section{Demo} + +\section{Conclusion} + +\begin{frame}{Drawbacks} + \begin{itemize} + \item Haskell has no custom open kinds (yet) + \item Proxies are ugly + \item Errors can be a bit daunting + \end{itemize} +\end{frame} + +\begin{frame}{Questions?} + Ølkartet: github.com/tazjin/pubkartet \\ + Slides: github.com/tazjin/servant-presentation + + @tazjin +\end{frame} +\end{document} |