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09fc7f8fa9
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202d130d33
11 changed files with 122 additions and 170 deletions
1
.gitignore
vendored
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.gitignore
vendored
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@ -51,4 +51,3 @@ slides/*.pdf
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_region_.tex
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*.xdv
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thesis/_minted-main/
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slides/_minted-main/
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@ -1,16 +0,0 @@
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variables:
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LATEX_IMAGE: danteev/texlive
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build:
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image: $LATEX_IMAGE
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script:
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- cd thesis
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- latexmk -pdf -xelatex -shell-escape main.tex
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- cd ../slides
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- latexmk -pdf -xelatex -shell-escape main.tex
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artifacts:
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paths:
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- "thesis/*.pdf"
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- "slides/*.pdf"
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2
slides/.vscode/settings.json
vendored
2
slides/.vscode/settings.json
vendored
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@ -7,9 +7,7 @@
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"-synctex=1",
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"-interaction=nonstopmode",
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"-file-line-error",
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"-shell-escape",
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"-pdf",
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"-xelatex",
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"-outdir=%OUTDIR%",
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"main.tex"
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],
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@ -3,12 +3,10 @@ hd [] = error "empty list"
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hd (x : _) = x
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main :: IO ()
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main = do
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print (Main.reverse ([1,2,3]::[Int]))
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print (hd []::[String])
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main = print (hd []::[String])
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reverse :: [a] -> [a]
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reverse l = reverseAcc l []
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reverse l = rev l []
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where
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reverseAcc [] a = a
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reverseAcc (x:xs) a = reverseAcc xs (x:a)
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rev [] a = a
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rev (x:xs) a = rev xs (x:a)
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@ -13,12 +13,16 @@ module reverse where
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now : A → Delay A
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later : ∞ (Delay A) → Delay A
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foldl : ∀ {A B : Set} → (A → B → A) → A → Colist B → Delay A
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foldl c n [] = now n
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foldl c n (x ∷ xs) = later (♯ foldl c (c n x) (♭ xs))
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-- reversing possibly infinite lists
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reverse : ∀ {A : Set} → Colist A → Delay (Colist A)
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reverse {A} = reverseAcc []
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where
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reverseAcc : Colist A → Colist A → Delay (Colist A)
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reverseAcc [] a = now a
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reverseAcc (x ∷ xs) a = later (♯ reverseAcc (♭ xs) (x ∷ (♯ a)))
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reverseAcc = foldl (λ xs x → x ∷ (♯ xs)) -- 'flip _∷_' with extra steps
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run_for_steps : ∀ {A : Set} → Delay A → ℕ → Delay A
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run now x for n steps = now x
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@ -24,8 +24,8 @@
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]{styles/beamerthemefau}
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% ----------------------------------------------------------------------------------------
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% Input and output encoding
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% \usepackage[T1]{fontenc}
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% \usepackage[utf8]{inputenc}
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\usepackage[T1]{fontenc}
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\usepackage[utf8]{inputenc}
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% ----------------------------------------------------------------------------------------
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% Language settings
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\usepackage[english]{babel}
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@ -36,7 +36,6 @@
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% - We use serif for math environements
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% - isomath is used for upGreek letters
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% ----------------------------------------------------------------------------------------
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\usepackage{fvextra}
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\usepackage{isomath}
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\usefonttheme[onlymath]{serif}
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\usepackage{exscale}
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@ -50,7 +49,7 @@
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% ========================================================================================
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% Setup for Titlepage
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% ----------------------------------------------------------------------------------------
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\title{Implementing Categorical Notions of Partiality and Delay in Agda}
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\title{Implementing Notions of Partiality and Delay\\ in Agda}
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\subtitle{Subtitle}
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\author[L. Vatthauer]{
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Leon Vatthauer%\inst{1}
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@ -139,20 +138,71 @@ Leon Vatthauer%\inst{1}
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% The main document
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% ------------------------------------------------
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\usepackage{MnSymbol} % for \squaredots
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\usepackage{minted}
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\setminted[agda]{
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linenos=true,
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\usepackage{listings}
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\lstset{mathescape}
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\usepackage{xcolor}
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\definecolor{codegray}{rgb}{0.5,0.5,0.5}
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\definecolor{string}{HTML}{79731B}
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\definecolor{keyword}{HTML}{447A59}
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\definecolor{background}{HTML}{E6E6E6}
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\definecolor{error}{HTML}{9B0511}
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\definecolor{agda-name}{HTML}{3b31f9}
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\definecolor{agda-keyword}{HTML}{fc970a}
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\definecolor{agda-constructor}{HTML}{08aa20}
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\lstdefinestyle{mystyle}{
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backgroundcolor=\color{background},
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% commentstyle=\color{codegreen},
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% keywordstyle=\color{keyword},
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numberstyle=\tiny\color{codegray},
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stringstyle=\color{string},
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basicstyle=\ttfamily\small,
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breakatwhitespace=false,
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breaklines=true,
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encoding=utf8,
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fontsize=\small,
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% frame=lines
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captionpos=b,
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keepspaces=true,
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numbers=left,
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numbersep=5pt,
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showspaces=false,
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showstringspaces=false,
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showtabs=false,
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tabsize=2
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}
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\lstdefinelanguage{myhaskell}{
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keywords=[1]{
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where
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},
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keywordstyle=[1]\color{agda-keyword},
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keywords=[2]{
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error
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},
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keywordstyle=[2]\color{error},
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keywords=[3]{
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head, reverse, rev
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},
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keywordstyle=[3]\color{agda-name},
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morestring=[b]"
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}
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\usepackage{multicol}
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\lstdefinelanguage{myagda}{
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keywords=[1]{
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data, where
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},
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keywordstyle=[1]\color{agda-keyword},
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keywords=[2]{
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Delay, Set, foldl, Colist, reverse, reverseAcc, run_for_steps, run, for, steps, fin-colist, inf-colist, never, head, List, Maybe
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},
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keywordstyle=[2]\color{agda-name},
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keywords=[3]{
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now, later, zero, suc, just, nothing, nil, cons
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},
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keywordstyle=[3]\color{agda-constructor}
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||||
}
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\usepackage{noto-mono}
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% \usepackage{fontspec}
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% \setmonofont{Noto Sans Mono}
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||||
\lstset{style=mystyle}
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\usepackage{lmodern}
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|
@ -186,8 +236,6 @@ at (#3) {#4};
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\end{frame}
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\input{sections/00_intro.tex}
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\input{sections/01_abstracting.tex}
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\input{sections/02_goals.tex}
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% Stylized outline
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%\begin{frame}[title]{-}
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|
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@ -1,29 +1,27 @@
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\section{Partiality in Type Theory}
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\begin{frame}[t, fragile]{Partiality in Haskell}{}
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\begin{itemize}
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\item<1-> Haskell allows users to define arbitrary partial functions, some can be spotted easily by their definition:
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\begin{itemize}[<+->]
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\item Haskell allows users to define arbitrary partial functions, some can be spotted easily by their definition:
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\vskip 1cm
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\begin{minted}{agda}
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\begin{lstlisting}[language=myhaskell, linewidth=12cm]
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head :: [a] -> a
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head [] = error "empty list"
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head (x:xs) = x
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\end{minted}
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\mycallout<2->{21, 1.5}{
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\end{lstlisting}
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\mycallout<3->{21, 1.5}{
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ghci> head []\\
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*** Exception: empty list\\
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CallStack (from HasCallStack):\\
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error, called at example.hs:2:9 in main:Main
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}
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\item<3->
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\item
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others might be more subtle:
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\vskip 1cm
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\begin{minted}{agda}
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||||
reverse :: [a] -> [a]
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reverse l = reverseAcc l []
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||||
where
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reverseAcc [] a = a
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||||
reverseAcc (x:xs) a = reverseAcc xs (x:a)
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||||
\end{minted}
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||||
\begin{lstlisting}[language=myhaskell, linewidth=12cm]
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reverse l = rev l []
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||||
where
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rev [] a = a
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||||
rev (x:xs) a = rev xs (x:a)
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\end{lstlisting}
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\mycallout<4->{21, 2}{
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ghci> ones = 1 : ones\\
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@ -32,6 +30,7 @@ reverse l = reverseAcc l []
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}
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||||
\end{itemize}
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% TODO right of this add error bubble that shows `reverse ones`
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\end{frame}
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\begin{frame}[t, fragile]{Partiality in Agda}{The Maybe Monad}
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|
@ -39,56 +38,59 @@ In Agda every function has to be total and terminating, so how do we model parti
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|||
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\begin{itemize}[<+->]
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||||
\item Simple errors can be modelled with the maybe monad
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\begin{minted}{agda}
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\begin{lstlisting}[linewidth=14cm, language=myagda]
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data Maybe (A : Set) : Set where
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just : A → Maybe A
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just : A $\rightarrow$ Maybe A
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nothing : Maybe A
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\end{minted}
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||||
\end{lstlisting}
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||||
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||||
for head we can then do:
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||||
\begin{minted}{agda}
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head : ∀ A → List A → Maybe A
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\begin{lstlisting}[linewidth=14cm, language=myagda]
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head : $\forall$ A $\rightarrow$ List A $\rightarrow$ Maybe A
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head nil = nothing
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head (cons x xs) = just x
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\end{minted}
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\end{lstlisting}
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||||
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||||
\item What about \mintinline{agda}|reverse|?
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\item What about \lstinline|reverse|?
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\end{itemize}
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\end{frame}
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||||
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\begin{frame}[t, fragile]{Partiality in Agda}{Capretta's Delay Monad}
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\begin{itemize}[<+->]
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\item Capretta's Delay Monad is a \textbf{coinductive} data type whose inhabitants can be viewed as suspended computations.
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\begin{minted}{agda}
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\begin{lstlisting}[linewidth=20cm, language=myagda]
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data Delay (A : Set) : Set where
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now : A → Delay A
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later : ∞ (Delay A) → Delay A
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\end{minted}
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now : A $\rightarrow$ Delay A
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later : $\infty$ (Delay A) $\rightarrow$ Delay A
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\end{lstlisting}
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\item The delay datatype contains a constant for non-termination:
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\begin{minted}{agda}
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\begin{lstlisting}[linewidth=20cm, language=myagda]
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never : Delay A
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never = later (♯ never)
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\end{minted}
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never = later ($\sharp$ never)
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\end{lstlisting}
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\item and we can define a function for \textit{running} a computation (for some amount of steps):
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\begin{minted}{agda}
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run_for_steps : Delay A → ℕ → Delay A
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\begin{lstlisting}[linewidth=20cm, language=myagda]
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run_for_steps : Delay A $\rightarrow$ $\mathbb{N}$ $\rightarrow$ Delay A
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run now x for n steps = now x
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run later x for zero steps = later x
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run later x for suc n steps = run ♭ x for n steps
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\end{minted}
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run later x for suc n steps = run $\flat$ x for n steps
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\end{lstlisting}
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\end{itemize}
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\end{frame}
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||||
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||||
\begin{frame}[c, fragile]{Partiality in Agda}{Reversing (possibly infinite) lists}
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\centering
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\begin{minted}{agda}
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reverse : ∀ {A : Set} → Colist A → Delay (Colist A)
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||||
\begin{lstlisting}[language=myagda]
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foldl : $\forall$ {A B : Set} $\rightarrow$ (A $\rightarrow$ B $\rightarrow$ A) $\rightarrow$ A $\rightarrow$ Colist B $\rightarrow$ Delay A
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foldl c n [] = now n
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foldl c n (x $\squaredots$ xs) = later ($\sharp$ foldl c (c n x) ($\flat$ xs))
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reverse : $\forall$ {A : Set} $\rightarrow$ Colist A $\rightarrow$ Delay (Colist A)
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reverse {A} = reverseAcc []
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||||
where
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reverseAcc : Colist A → Colist A → Delay (Colist A)
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||||
reverseAcc [] a = now a
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||||
reverseAcc (x ∷ xs) a = later (♯ reverseAcc (♭ xs) (x ∷ (♯ a)))
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||||
\end{minted}
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||||
reverseAcc : Colist A $\rightarrow$ Colist A $\rightarrow$ Delay (Colist A)
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||||
reverseAcc = foldl ($\lambda$ xs x $\rightarrow$ x $\squaredots$ ($\sharp$ xs))
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||||
\end{lstlisting}
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||||
\end{frame}
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@ -1,56 +0,0 @@
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\section{Categorical Notions of Partiality}
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||||
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% \begin{frame}[t, fragile]{Classifying Partiality Monads}
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% A partiality monad should have the following properties:
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% \begin{itemize}
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% \item The following two programs should yield equal results:
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% \begin{multicols}{2}
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% \begin{minted}{haskell}
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% do x <- p
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||||
% y <- q
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||||
% return (x, y)
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% \end{minted}
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||||
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||||
% \begin{minted}{haskell}
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||||
% do y <- q
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||||
% x <- p
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||||
% return (x, y)
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||||
% \end{minted}
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||||
% \end{multicols}
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||||
% where p and q are (partial) computations.
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||||
% \end{itemize}
|
||||
% \end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{Capturing Partiality Categorically}
|
||||
\begin{itemize}
|
||||
\item moggi denotational semantics (values A, computations TA)
|
||||
|
||||
\item restriction categories
|
||||
|
||||
\item equational lifting monads
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{The Maybe Monad}
|
||||
\begin{itemize}
|
||||
\item Short definition
|
||||
\item is equational lifting monad
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{The Delay Monad}
|
||||
\begin{itemize}
|
||||
\item Definition
|
||||
\item Strong-Bisimilarity
|
||||
\item Weak-Bisimilarity (Monad?)
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{Iteration}
|
||||
\begin{itemize}
|
||||
\item Elgot-Algebras
|
||||
\item Free Elgot-Algebras yield monad K
|
||||
\item K is equational lifting
|
||||
\item K instantiates to maybe and delay
|
||||
\end{itemize}
|
||||
\end{frame}
|
|
@ -1,24 +0,0 @@
|
|||
\section{Implementation in Agda}
|
||||
|
||||
\begin{frame}[t, fragile]{Goals}
|
||||
\begin{itemize}
|
||||
\item Formalize delay monad (categorically as terminal coalgebra) + properties
|
||||
\item Formalize K + properties
|
||||
\item Case study on Setoids
|
||||
\end{itemize}
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{Category theory in Agda}
|
||||
agda-categories
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{What I managed to show}
|
||||
TODO
|
||||
\end{frame}
|
||||
|
||||
\begin{frame}[t, fragile]{Further work}
|
||||
\begin{itemize}
|
||||
\item Show that $\tilde{D}$ is monad (under conditions)
|
||||
\item Show that $K \cong \tilde{D}$ (under conditions)
|
||||
\end{itemize}
|
||||
\end{frame}
|
|
@ -53,7 +53,7 @@
|
|||
\chaptermark{#1}%
|
||||
\addcontentsline{toc}{chapter}{#1}}
|
||||
|
||||
%\newcommand\C{\mathcal{C}}
|
||||
\newcommand\C{\mathcal{C}}
|
||||
|
||||
\declaretheorem[name=Definition,style=definition,numberwithin=chapter]{definition}
|
||||
\declaretheorem[name=Example,style=definition,sibling=definition]{example}
|
||||
|
@ -90,9 +90,8 @@
|
|||
\newcommand*{\theauthor}{\@author}
|
||||
\makeatother
|
||||
|
||||
\usepackage{noto-mono}
|
||||
%\usepackage{fontspec}
|
||||
%\setmonofont{Noto Sans Mono}
|
||||
\usepackage{fontspec}
|
||||
\setmonofont{Noto Sans Mono}
|
||||
|
||||
|
||||
\begin{document}
|
||||
|
|
|
@ -149,7 +149,7 @@ When modelling partiality with a monad, one would expect the following two progr
|
|||
\end{multicols}
|
||||
where p and q are (partial) computations. This condition can be expressed categorically, but first we need another definition:
|
||||
|
||||
\begin{definition}[Strong Monad~\cite{moggi}] A monad $M$ on a cartesian category $\mathcal{C}$ is called strong if there exists a natural transformation $\tau_{X,Y} : X \times MY \rightarrow M(X \times Y)$, satisfying the following conditions:
|
||||
\begin{definition}[Strong Monad~\cite{moggi}] A monad $M$ on a cartesian category $\C$ is called strong if there exists a natural transformation $\tau_{X,Y} : X \times MY \rightarrow M(X \times Y)$, satisfying the following conditions:
|
||||
\begin{enumerate}
|
||||
\item $M\pi_2 \circ \tau_{1,X} = \pi_2$
|
||||
\item $M \alpha_{X,Y,Z} \circ \tau_{X \times Y, Z} = \tau_{X, Y\times Z} \circ (id_X \times \tau_{Y, Z}) \circ \alpha_{X,Y,MZ}$
|
||||
|
|
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Reference in a new issue