Finished first draft of Python-part.

Notes.md

@@ -19,22 +19,22 @@ html header:    <link rel="stylesheet"
    + currying => just convenience
    + code example: Pythagoraian triangles, bubble sort
  * Phuncy: The pythonic way is functional!
-   - Not strictly functional
+   + Not strictly functional
-   - recursion, fafco
+   - recursion
-   - lambda syntax
+   + fafco
    - map, fold => example (sum of squares?)
-     - python lambda syntax: lambda a,b: a+b
+     + python lambda syntax: lambda a,b: a+b
-     - fold with reduce
+     + don't return lists, but iterators!
-     - don't return lists, but iterators!
+     + fold with reduce
-     - Note: 2: map, filter, reduce, list comprehension
+     + Note: 2: map, filter, reduce, list comprehension
              3: map, filter, functools.reduce(), list comprehension
 
 
-     - The python2 to 3 page states:
+     + The python2 to 3 page states:
        “Removed `reduce()`. Use `functools.reduce()` if you really need it;
        however, 99 percent of the time an explicit `for` loop is more
        readable.”
-     - Why use it? => Multi-processing, WTF Count.
+     + Why use it? => Multi-processing, WTF Count.
        
        ```python
        a = list(range(10))
@@ -50,7 +50,7 @@ html header:    <link rel="stylesheet"
        from functools import reduce
        print(reduce(lambda x,y: x+y,map(lambda x: x**2,range(10))))
        ```
-   - currying: not really, but binding via lambdas or functools.partial() or
+   + currying: not really, but binding via lambdas or functools.partial() or
                https://mtomassoli.wordpress.com/2012/03/18/currying-in-python/
    - decorators!
    - still FP has advantages and is heavily used, i.e. in genomics (works on

tex/headers/listings.tex

@@ -39,9 +39,22 @@
   fontsize=\small,
 }
 
+\newminted[pycode]{python}%
+{
+  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}{}
+\newmintinline[pycmd]{python}{}
 
 %%% Local Variables:
 %%% mode: latex

tex/wtf.bib

@@ -2,4 +2,10 @@
 title={Foldr Foldl Foldl' - HaskellWiki},
 urldate={2016-04-21},
 url={https://wiki.haskell.org/Foldr_Foldl_Foldl%27},
+}
+
+@online{decorators,
+title={simeonfranklin.com - Understanding Python Decorators in 12 Easy Steps!},
+urldate={2016-04-25},
+url={http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/},
 }

tex/wtfunctional.tex

@@ -3,7 +3,7 @@
 \usepackage{babel}
 \usepackage{csquotes}
 \usepackage{tabularx}
-\usepackage[backend=biber, style=numeric,]{biblatex}
+\usepackage[backend=biber,]{biblatex}
 \bibliography{wtf}
 
 \usepackage{fontspec}
@@ -39,18 +39,18 @@
 \end{frame}
 
 \begin{frame}[fragile]{Example}
-    %ToDo: C-code call by value, call by reference.
+    % ToDo: C-code call by value, call by reference.
-    \begin{cppcode}
+\begin{cppcode}
-        int f(int  x) { return ++x;}
+int f(int  x) { return ++x;}
-        int g(int& x) { return ++x;}
+int g(int& x) { return ++x;}
-        int main() {
+int main() {
-          int x = 2;
+  int x = 2;
-          f(x);
+  f(x);
-          assert(x==2); // f is “functional”
+  assert(x==2); // f is “functional”
-          g(x);
+  g(x);
-          assert(x!=2); // g is not!
+  assert(x!=2); // g is not!
-        }
+}
-    \end{cppcode}
+\end{cppcode}
 \end{frame}
 
 \begin{frame}{Pros and Cons}
@@ -83,19 +83,19 @@
 
 \begin{frame}[fragile]{Syntax – Functions}
     Function constraints, definition and calls:
-    \begin{haskell}
+\begin{haskell}
-        mysum :: Num a => a -> a -> a -> a
+mysum :: Num a => a -> a -> a -> a
-        mysum x y z = x + y + z
+mysum x y z = x + y + z
-        -- b == 6
+-- b == 6
-        b = mysum 1 2 3
+b = mysum 1 2 3
-    \end{haskell}
+\end{haskell}
     \pause
     Functions always get evaluated left to right, thus the following works (\emph{Currying}):
-    \begin{haskell}
+\begin{haskell}
-        mysum2 = mysum 2
+mysum2 = mysum 2
-        -- c == 12
+-- c == 12
-        c = mysum2 4 6
+c = mysum2 4 6
-    \end{haskell}
+\end{haskell}
 \end{frame}
 
 \begin{frame}[fragile]{Syntax – Lists (1)}
@@ -117,26 +117,26 @@
     \item Two lists can be concatenated using the \haskellcmd{++} operator:
         \haskellcmd{[1,2,3] ++ [4..7]}
     \item Single objects get pushed to the front using
-        \enquote{\haskellcmd{:}}: \haskellcmd{1:[2..7]}.    
+        \enquote{\haskellcmd{:}}: \haskellcmd{1:[2..7]}.
     \item This can also be used vice versa to extract single values from lists:
-        \begin{haskell}
+\begin{haskell}
-            extract (x:xs) = x
+extract (x:xs) = x
-            -- a = 1
+-- a = 1
-            a = extract [1..5]
+a = extract [1..5]
-        \end{haskell}
+\end{haskell}
     \end{itemize}
 \end{frame}
-    
+
 \begin{frame}[fragile]{Syntax – Recursion}
     Example: Add a value to every entry in an array
-    \begin{haskell}
+\begin{haskell}
-        addto :: (Num a) => [a] -> a -> [a]
+addto :: (Num a) => [a] -> a -> [a]
-        addto [] _ = [] -- edge case (list empty)
+addto [] _ = [] -- edge case (list empty)
-        addto (x:xs) y = (x+y) : addto xs y
+addto (x:xs) y = (x+y) : addto xs y
-        b = [1..4]
+b = [1..4]
-        -- c == [5,6,7,8]
+-- c == [5,6,7,8]
-        c = addto b 4
+c = addto b 4
-    \end{haskell}
+\end{haskell}
 \end{frame}
 
 \begin{frame}[fragile]{Lambdas}
@@ -169,52 +169,147 @@
 \end{frame}
 
 \begin{frame}[fragile]{Folds (2)}
-    \uncover<+-> Example: Self written Right fold and sum: 
+    \uncover<+-> Example: Self written Right fold and sum:
-    \begin{haskell}
+\begin{haskell}
-        mfold f z [] = z
+mfold f z [] = z
-        mfold f z (x:xs) = f x (mfold f z xs)
+mfold f z (x:xs) = f x (mfold f z xs)
-        msum = mfold (+) 0
+msum = mfold (+) 0
-        -- g == 5050
+-- g == 5050
-        g = msum [1..100]
+g = msum [1..100]
-    \end{haskell}
+\end{haskell}
     \uncover<+->{Note that this gets pretty resource hungry with large
       lists, better use left-folds for this (see~\cite{whichfold})}
 \end{frame}
 
 \begin{frame}[fragile]{Example: Pythagorean triangles}
     Get all Pythagorean triangles with a hypotenuse off length at most 15:
-    \begin{haskell}
+\begin{haskell}
-        > [(a,b,c) | a <- [1..15],
+> [(a,b,c) | a <- [1..15],
-                     b <- [1..a],
+b <- [1..a],
-                     c <- [1..b],
+c <- [1..b],
-                     a^2 == b^2 + c^2]
+a^2 == b^2 + c^2]
-        [(5,4,3),(10,8,6),(13,12,5),(15,12,9)]
+[(5,4,3),(10,8,6),(13,12,5),(15,12,9)]
-    \end{haskell}
+\end{haskell}
-\end{frame}    
+\end{frame}
 
 \begin{frame}[fragile]{Example: Bubble-sort}
     Recursive, functional bubble-sort algorithm:
-    \begin{haskell}
+\begin{haskell}
-        bsort f [] = []
+bsort f [] = []
-        bsort f (x:xs) = (bsort f a) ++ [x] ++ (bsort f b)
+bsort f (x:xs) = (bsort f a) ++ [x] ++ (bsort f b)
-          where a = [ y | y <- xs, not (f x y) ]
+where a = [ y | y <- xs, not (f x y) ]
-                b = [ y | y <- xs, (f x y) ]
+b = [ y | y <- xs, (f x y) ]
-        mbsort = bsort (\x y -> (x > y))
+mbsort = bsort (\x y -> (x > y))
-    \end{haskell}
+\end{haskell}
     \pause Result:
-    \begin{haskell}
+\begin{haskell}
-        λ> h = [1, 20, -10, 5]
+λ> h = [1, 20, -10, 5]
-        λ> mbsort h
+λ> mbsort h
-        [-10,1,5,29]
+[-10,1,5,29]
-    \end{haskell}
+\end{haskell}
+\end{frame}
+
+\section{Phuncy!}
+\subsection{Overview}
+\begin{frame}{Functional programming in Python}
+    \begin{itemize}[<+->]
+    \item Obviously, python is not strictly functional…
+    \item …but has functions as first class objects!
+    \item Some other stuff is widely used, but with another syntax…
+    \item …, although there are ways to get the \enquote{real} functional
+        style.
+    \item I use python3 here, python2 differs in some points.
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Lambdas, Maps}
+    \begin{itemize}[<+->]
+    \item Lambda-syntax: \pycmd{lambda a,b: a+b}
+    \item Maps are done by \pycmd{map}
+    \item \emph{Note:} Most functional list-functions return iterators in
+        python, not lists!
+    \item Use \pycmd{list()} to cast Iterators, but this is usually not
+        necessary.
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Filters}
+    \begin{itemize}[<+->]
+    \item Can be done using \pycmd{filter(func, iter)}:
+\begin{pycode}
+a = range(1,7)
+b = filter(lambda x: x%2, a)
+print(list(b))
+# [1,3,5]
+\end{pycode}
+    \item Alternatively, use List Comprehension:
+\begin{pycode}
+a = range(1,7)
+b = [x for x in a if x%2]
+print(b)
+\end{pycode}
+    \item Pro: Maybe easier readable, returns list
+    \item Con: Returns list (slower when iterating afterwards)
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Fold}
+    \begin{itemize}[<+->]
+    \item From the python2 to python3 Changelog:
+        \begin{quote}
+            Removed `reduce()`. Use `functools.reduce()` if you really need it;
+            however, 99 percent of the time an explicit `for` loop is more
+            readable.
+        \end{quote}
+    \item I disagree – Old-style is more explicit and  still available from \pycmd{functools}
+    \item Example – sum of squares
+\begin{pycode}
+from functools import reduce
+a = range(10)
+mapped = map(lambda x: x**2, a)
+reduced = reduce(lambda x,y: x+y, mapped)
+\end{pycode}
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Currying}
+    \begin{itemize}[<+->]
+    \item No real currying, but several workarounds
+    \item Lambdas: \pycmd{g=lambda x: foo(2,x)}
+    \item \pycmd{functools.partial}:
+\begin{pycode}
+def foo(x,y):
+  return x+y
+bar=partial(foo, 2)
+bar(3) # 5
+\end{pycode}
+    \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]{Decorators}
+    \begin{itemize}[<+->]
+    \item Often used to modify functions in Frameworks
+    \item Encapsulates other functions. More infos at \cite{decorators}
+\begin{pycode}
+def debug(func):
+  def inner(*args, **kwargs):
+    sys.stderr.write("F: {}, args: {}, kwargs {}".format(func.__name__, args,
+    kwargs))
+    return func(*args, **args)
+  return inner
+@debug
+def foo(x):
+  print(x)
+\end{pycode}
+    \end{itemize}
 \end{frame}
 
 \begin{frame}[plain]{References}
     \printbibliography
-\end{frame}          
+\end{frame}
 \end{document}
 
 %%% Local Variables:
 %%% mode: latex
-%%% ispell-dictionary: en
+%%% ispell-local-dictionary: "en_GB"
 %%% End: