First draft of talk:

* Dafunc? concetpually almost ready
 * Started haskell introduction

.gitignore

@@ -17,7 +17,7 @@
 # these rules might exclude image files for figures etc.
 # *.ps
 # *.eps
-# *.pdf
+*.pdf
 
 ## Bibliography auxiliary files (bibtex/biblatex/biber):
 *.bbl

examples/00_dafunc.cpp

@@ -0,0 +1,18 @@
+#include <iostream>
+#include <cassert>
+using namespace std;
+
+int f(int  x) { return ++x;}
+int g(int& x) { return ++x;}
+int main() {
+    int x = 2;
+    /* f is "functional", as it has no side-effects */
+    f(x);
+    assert(x==2);
+    /* g changes a variable of an outer scope,
+     * i.e. it has a side effect
+     * Thus, g is not functional!
+     */
+    g(x);
+    assert(x!=2);
+}

examples/01_haskell_recursion.hs

@@ -0,0 +1,12 @@
+extract :: [a] -> a
+extract [] = error("Too few objects")
+extract (x:xs) = x
+a = extract [1,2,3,4,5]
+
+addto :: (Num a) => [a] -> a -> [a]
+addto [] _ = [] -- edge case (list empty)
+addto (x:xs) y = (x+y) : addto xs y
+b = [1..4]
+-- c == [5,6,7,8]
+c = addto b 4
+

tex/headers/listings.tex

@@ -0,0 +1,49 @@
+\ProvidesFile{listings}[Configure listings with minted]
+% Fix backticks
+\usepackage{upquote}
+\usepackage[section, cache=true,]{minted}
+
+\newminted[ccode]{c}%
+{
+  linenos=true,
+  autogobble=true,
+  breaklines=true,
+  showspaces=false,
+  showtabs=false,
+  tabsize=2,
+  frame=single,
+  fontsize=\small,
+}
+
+\newminted[cppcode]{cpp}%
+{
+  linenos=true,
+  autogobble=true,
+  breaklines=true,
+  showspaces=false,
+  showtabs=false,
+  tabsize=2,
+  frame=single,
+  fontsize=\small,
+}
+
+\newminted[haskell]{haskell}
+{
+  linenos=true,
+  autogobble=true,
+  breaklines=true,
+  showspaces=false,
+  showtabs=false,
+  tabsize=2,
+  frame=single,
+  fontsize=\small,
+}
+
+\newmintinline[ccmd]{c}{}
+\newmintinline[cppcmd]{cpp}{}
+\newmintinline[haskellcmd]{haskell}{}
+
+%%% Local Variables:
+%%% mode: latex
+%%% TeX-master: "../linux-script"
+%%% End:

tex/wtfunctional.tex

@@ -0,0 +1,146 @@
+\documentclass[english]{beamer}
+
+\usepackage{babel}
+\usepackage{csquotes}
+\usepackage{tabularx}
+
+\usepackage{fontspec}
+\setsansfont{Fira Sans}
+\setmonofont{Inconsolata-g}
+
+\usetheme{Antibes}
+%\usecolortheme{beaver}
+\setbeamercovered{transparent}
+
+\title{WTFunctional}
+\author{Oliver Rümpelein}
+\subtitle{Using functional structures in non-functional languages}
+
+\input{headers/listings}
+
+\begin{document}
+\frame{\titlepage}
+
+\section{Dafunc?}
+\subsection{Functional programming}
+\begin{frame}{Understanding functional paradigms}
+    Here: so called \enquote{purely functional} paradigm.
+    \begin{itemize}
+    \item<+-> Programming without \enquote{side-effects}
+        \begin{itemize}
+        \item<+-> No mutability
+        \item<+-> Functions work only in local context
+        \end{itemize}
+    \item<+-> Extensive use of lists and so called maps/reduces (later)
+    \item<+-> Do not mix up with \enquote{procedural} programming (using only functions)!
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Example}
+    %ToDo: C-code call by value, call by reference.
+    \begin{cppcode}
+        int f(int  x) { return ++x;}
+        int g(int& x) { return ++x;}
+        int main() {
+          int x = 2;
+          f(x);
+          assert(x==2); // f is “functional”
+          g(x);
+          assert(x!=2); // g is not!
+        }
+    \end{cppcode}
+\end{frame}
+
+\begin{frame}{Pros and Cons}
+    Pros:
+    \begin{itemize}[<+->]
+    \item Maintainability
+    \item Testing
+    \item (often) shorter code
+    \end{itemize}
+    Cons:
+    \begin{itemize}[<+->]
+    \item harder to learn
+    \item harder to understand
+    \item slower due to abstraction
+    \end{itemize}
+\end{frame}
+
+\subsection{Case study: Haskell}
+\begin{frame}{Overview}
+    \begin{itemize}[<+->]
+    \item \emph{Haskell} is a purely functional, compiled programming language
+        developed since 1990.
+    \item It is typed and has a strong meta-type system (comparable to
+        interfaces in OOP)
+    \item The most important implementation is \emph{GHC} (Glasgow Haskell
+        Compiler)
+    \item Haskell is lazy. Statements get evaluated only when needed, if ever.
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Syntax – Functions}
+    Function constraints, definition and calls:
+    \begin{haskell}
+        mysum :: Num a => a -> a -> a -> a
+        mysum x y z = x + y + z
+        -- b == 6
+        b = mysum 1 2 3
+    \end{haskell}
+    \pause
+    Functions always get evaluated left to right, thus the following works (\emph{Currying}):
+    \begin{haskell}
+        mysum2 = mysum 2
+        -- c == 12
+        c = mysum2 4 6
+    \end{haskell}
+\end{frame}
+
+\begin{frame}[fragile]{Syntax – Lists (1)}
+    Lists in Haskell can only hold data of one type. They are defined using
+    \haskellcmd{a = [1,2,3,4]} or similar.
+
+    \pause
+    Furthermore, an automatic range can be obtained by using
+    \haskellcmd{b = [1..4]}, where the last number is inclusive.
+
+    \pause
+    If possible, Haskell will try to inhibit the step automatically
+    \haskellcmd{c = [1,3..7]} yields \haskellcmd{[1,3,5,7]}.
+
+    \pause
+    When leaving out the end specifier, a range can be infinite. In this case,
+    it's up to the programmer to constrain things.
+\end{frame}
+
+\begin{frame}[fragile]{Syntax – Lists (2)}
+    Two arrays can be concatenated using the \haskellcmd{++} operator
+    \haskellcmd{[1,2,3] ++ [4..7]}
+
+    Single objects get pushed to the front using \haskellcmd{:}:
+    \haskellcmd{1:[2..7]}.    
+
+    This can also be used vice versa to extract single values from lists
+    \begin{haskell}
+        extract (x:xs) = x
+        -- a = 1
+        a = extract [1..5]
+    \end{haskell}
+\end{frame}
+
+\begin{frame}[fragile]{Syntax – Recursion}
+    Example: Add a value to every entry in an array
+    \begin{haskell}
+        addto :: (Num a) => [a] -> a -> [a]
+        addto [] _ = [] -- edge case (list empty)
+        addto (x:xs) y = (x+y) : addto xs y
+        b = [1..4]
+        -- c == [5,6,7,8]
+        c = addto b 4
+    \end{haskell}
+\end{frame}
+\end{document}
+
+%%% Local Variables:
+%%% mode: latex
+%%% End: