Finished first draft of Python-part.
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4 changed files with 193 additions and 79 deletions
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Notes.md
20
Notes.md
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@ -19,22 +19,22 @@ html header: <link rel="stylesheet"
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+ currying => just convenience
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+ currying => just convenience
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+ code example: Pythagoraian triangles, bubble sort
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+ code example: Pythagoraian triangles, bubble sort
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* Phuncy: The pythonic way is functional!
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* Phuncy: The pythonic way is functional!
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- Not strictly functional
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+ Not strictly functional
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- recursion, fafco
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- recursion
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- lambda syntax
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+ fafco
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- map, fold => example (sum of squares?)
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- map, fold => example (sum of squares?)
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- python lambda syntax: lambda a,b: a+b
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+ python lambda syntax: lambda a,b: a+b
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- fold with reduce
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+ don't return lists, but iterators!
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- don't return lists, but iterators!
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+ fold with reduce
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- Note: 2: map, filter, reduce, list comprehension
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+ Note: 2: map, filter, reduce, list comprehension
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3: map, filter, functools.reduce(), list comprehension
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3: map, filter, functools.reduce(), list comprehension
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- The python2 to 3 page states:
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+ The python2 to 3 page states:
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“Removed `reduce()`. Use `functools.reduce()` if you really need it;
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“Removed `reduce()`. Use `functools.reduce()` if you really need it;
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however, 99 percent of the time an explicit `for` loop is more
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however, 99 percent of the time an explicit `for` loop is more
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readable.”
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readable.”
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- Why use it? => Multi-processing, WTF Count.
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+ Why use it? => Multi-processing, WTF Count.
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```python
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```python
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a = list(range(10))
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a = list(range(10))
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@ -50,7 +50,7 @@ html header: <link rel="stylesheet"
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from functools import reduce
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from functools import reduce
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print(reduce(lambda x,y: x+y,map(lambda x: x**2,range(10))))
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print(reduce(lambda x,y: x+y,map(lambda x: x**2,range(10))))
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```
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```
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- currying: not really, but binding via lambdas or functools.partial() or
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+ currying: not really, but binding via lambdas or functools.partial() or
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https://mtomassoli.wordpress.com/2012/03/18/currying-in-python/
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https://mtomassoli.wordpress.com/2012/03/18/currying-in-python/
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- decorators!
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- decorators!
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- still FP has advantages and is heavily used, i.e. in genomics (works on
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- still FP has advantages and is heavily used, i.e. in genomics (works on
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@ -39,9 +39,22 @@
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fontsize=\small,
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fontsize=\small,
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}
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}
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\newminted[pycode]{python}%
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{
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linenos=true,
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autogobble=true,
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breaklines=true,
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showspaces=false,
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showtabs=false,
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tabsize=2,
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frame=single,
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fontsize=\small,
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}
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\newmintinline[ccmd]{c}{}
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\newmintinline[ccmd]{c}{}
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\newmintinline[cppcmd]{cpp}{}
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\newmintinline[cppcmd]{cpp}{}
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\newmintinline[haskellcmd]{haskell}{}
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\newmintinline[haskellcmd]{haskell}{}
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\newmintinline[pycmd]{python}{}
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%%% Local Variables:
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%%% Local Variables:
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%%% mode: latex
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%%% mode: latex
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@ -3,3 +3,9 @@ title={Foldr Foldl Foldl' - HaskellWiki},
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urldate={2016-04-21},
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urldate={2016-04-21},
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url={https://wiki.haskell.org/Foldr_Foldl_Foldl%27},
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url={https://wiki.haskell.org/Foldr_Foldl_Foldl%27},
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}
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}
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@online{decorators,
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title={simeonfranklin.com - Understanding Python Decorators in 12 Easy Steps!},
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urldate={2016-04-25},
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url={http://simeonfranklin.com/blog/2012/jul/1/python-decorators-in-12-steps/},
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}
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@ -3,7 +3,7 @@
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\usepackage{babel}
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\usepackage{babel}
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\usepackage{csquotes}
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\usepackage{csquotes}
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\usepackage{tabularx}
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\usepackage{tabularx}
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\usepackage[backend=biber, style=numeric,]{biblatex}
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\usepackage[backend=biber,]{biblatex}
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\bibliography{wtf}
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\bibliography{wtf}
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\usepackage{fontspec}
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\usepackage{fontspec}
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@ -209,6 +209,101 @@
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\end{haskell}
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\end{haskell}
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\end{frame}
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\end{frame}
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\section{Phuncy!}
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\subsection{Overview}
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\begin{frame}{Functional programming in Python}
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\begin{itemize}[<+->]
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\item Obviously, python is not strictly functional…
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\item …but has functions as first class objects!
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\item Some other stuff is widely used, but with another syntax…
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\item …, although there are ways to get the \enquote{real} functional
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style.
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\item I use python3 here, python2 differs in some points.
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\end{itemize}
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\end{frame}
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\begin{frame}[fragile]{Lambdas, Maps}
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\begin{itemize}[<+->]
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\item Lambda-syntax: \pycmd{lambda a,b: a+b}
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\item Maps are done by \pycmd{map}
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\item \emph{Note:} Most functional list-functions return iterators in
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python, not lists!
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\item Use \pycmd{list()} to cast Iterators, but this is usually not
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necessary.
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\end{itemize}
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\end{frame}
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\begin{frame}[fragile]{Filters}
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\begin{itemize}[<+->]
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\item Can be done using \pycmd{filter(func, iter)}:
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\begin{pycode}
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a = range(1,7)
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b = filter(lambda x: x%2, a)
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print(list(b))
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# [1,3,5]
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\end{pycode}
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\item Alternatively, use List Comprehension:
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\begin{pycode}
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a = range(1,7)
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b = [x for x in a if x%2]
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print(b)
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\end{pycode}
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\item Pro: Maybe easier readable, returns list
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\item Con: Returns list (slower when iterating afterwards)
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\end{itemize}
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\end{frame}
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\begin{frame}[fragile]{Fold}
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\begin{itemize}[<+->]
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\item From the python2 to python3 Changelog:
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\begin{quote}
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Removed `reduce()`. Use `functools.reduce()` if you really need it;
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however, 99 percent of the time an explicit `for` loop is more
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readable.
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\end{quote}
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\item I disagree – Old-style is more explicit and still available from \pycmd{functools}
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\item Example – sum of squares
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\begin{pycode}
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from functools import reduce
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a = range(10)
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mapped = map(lambda x: x**2, a)
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reduced = reduce(lambda x,y: x+y, mapped)
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\end{pycode}
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\end{itemize}
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\end{frame}
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\begin{frame}[fragile]{Currying}
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\begin{itemize}[<+->]
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\item No real currying, but several workarounds
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\item Lambdas: \pycmd{g=lambda x: foo(2,x)}
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\item \pycmd{functools.partial}:
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\begin{pycode}
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def foo(x,y):
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return x+y
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bar=partial(foo, 2)
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bar(3) # 5
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\end{pycode}
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\end{itemize}
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\end{frame}
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\begin{frame}[fragile]{Decorators}
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\begin{itemize}[<+->]
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\item Often used to modify functions in Frameworks
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\item Encapsulates other functions. More infos at \cite{decorators}
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\begin{pycode}
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def debug(func):
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def inner(*args, **kwargs):
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sys.stderr.write("F: {}, args: {}, kwargs {}".format(func.__name__, args,
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kwargs))
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return func(*args, **args)
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return inner
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@debug
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def foo(x):
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print(x)
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\end{pycode}
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\end{itemize}
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\end{frame}
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\begin{frame}[plain]{References}
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\begin{frame}[plain]{References}
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\printbibliography
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\printbibliography
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\end{frame}
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\end{frame}
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%%% Local Variables:
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%%% Local Variables:
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%%% mode: latex
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%%% mode: latex
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%%% ispell-dictionary: en
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%%% ispell-local-dictionary: "en_GB"
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%%% End:
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%%% End:
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