initial commit

.gitignore

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+*.o
+*.hi
+*~
+Mandelbulb
+hglmandel
+02_Edges/HGLMandelEdge

00_Introduction.lhs

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+ ## Introduction
+
+My last two post where about Haskell and how to do something useful with it.
+
+Now, it is time to talk about Categories.
+How this notion could help you and how it is easy to use with Haskell.
+
+- What are categories?
+- How to use them?
+
+First, a realisation.
+
+Programming paradigm. When you program, you resolve problems.
+There are a lot of different means to resolve a problem.
+Some general school of thought exists.
+
+In programming, most people use the imperative paradigm.
+You use some memory and update it.
+More precisely, you destroy part of information by setting variables to new values.
+Hidden somewhere, there is the model of the Turing machine.
+Of course, it is more complex with modern architecture, but the paradigm is the same.
+You have an infinite number of cell and you can write things on them.
+But you must erase them.
+
+Another paradigm, is the functional paradigm.
+This time, you don't write on cells, but instead you have a flow of data.
+And you transform the flows in another flows... Mostly it looks like pipes.
+I am a bit restrictive here. But generally this is how functional programming is perceived.
+The main theory behind this paradigm is the Set theory.
+You have a set and you go from one set to another set by using a function.
+
+But using I believe there is another paradigm arising from Category theory.
+And from what I saw up until there.
+Category theory is both more general and powerful to help solve problems.
+
+First, you must realize there are categories everywhere.
+With the category theory you can find relationships between quantum physics,
+topology, logic (both predicate and first order), programming.
+Most of the time, the object your are programming with will form a category.
+
+This is the promise from the Category Theory.
+Another even better paradigm.
+A paradigm with gates between many different domains.
+
+ ## Get some intuition
+
+We write down the definition first.
+And will discuss about some categories.
+
+ > **Definition**:
+ >
+ > A category \\(C\\) consist of:
+ >
+ > - A collection of _objects_ \\(ob(C)\\)
+ > - For every pair of objects \\((A,B)\\) a set \\(hom(A,B)\\)
+ >   of _morphisms_ \\(f:A→B\\) (Another notation for \\(f\in hom(A,B)\\))
+ > - A composition operator \\(∘\\)
+ >   which associate to each couple \\(g:A→B\\), \\(f:B→C\\) another morphism \\(f∘g:A→C\\).
+ >
+ > With the following properties
+ >
+ > - for each object \\(x\\) there is an identity morphism  
+ >   \\(id_x:x→x\\)  
+ >   s.t. for any morphism \\(f:A->B\\),  
+ >   \\(id_A∘f = f = f∘id_B\\)
+ > - for all triplet of morphisms \\(h:A->B\\), \\(g:B->C\\) and \\(f:C->D\\)  
+ >   \\( (f∘g)∘h = f∘(g∘h) \\)
+

config.ymd

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+-----
+isHidden:       false
+menupriority:   1
+kind:           article
+created_at:     2012-10-01T19:16:43+02:00
+en: title: Categeory Theory Programming
+fr: title: Programmation en Théorie des Catégories
+author_name: Yann Esposito
+author_uri: yannesposito.com
+tags:
+  - Haskell
+  - programming
+  - functional
+  - category theory
+-----
+
+begindiv(intro)
+
+en: %tldr How to program using category theory.
+fr: %tlal Comment programmer en utilisant la théorie des catégories.
+

create_ymd.sh

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+#!/usr/bin/env zsh
+
+function writeTOC() {
+
+cat <<END
+> <center><hr style="width:30%;float:left;border-color:#CCCCD0;margin-top:1em"/><span class="sc"><b>Table of Content</b></span><hr style="width:30%;float:right;border-color:#CCCCD0;margin-top:1em"/></center>
+> 
+> * This will be replaced by the ToC
+> {:toc}
+>
+END
+
+}
+
+cat config.ymd
+
+writeTOC
+
+cat <<END
+
+enddiv
+
+END
+
+for fic in **/*.lhs(.N); do
+    contains_haskell=$(( $( egrep '^>' $fic | wc -l) > 0 ))
+    ((contains_haskell)) && \
+        print -- "\n<hr/><a href=\"code/$fic\" class=\"cut\">Download the source code of this section → ${fic:h}/<strong>${fic:t}</strong></a>\n"
+    cat $fic
+    ((contains_haskell)) && \
+        print -- "\n<a href=\"code/$fic\" class=\"cut\">Download the source code of this section → ${fic:h}/<strong>${fic:t}</strong> </a>\n"
+done | perl -pe 'BEGIN{$/="";} s#((^>.*\n)+)#<div class="codehighlight">\n<code class="haskell">\n$1</code>\n</div>\n#mg' | perl -pe 's#^> ?##' | perl -pe 's/^ #/#/'

prev

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+#!/usr/bin/env zsh
+
+webroot="$HOME/Sites/webroot"
+
+print -- "Search script"
+while [[ ! -x ./create_ymd.sh ]]; do 
+    [[ $PWD = "/" ]] && {
+        print -- "Error: can't find create_ymd.sh" >&2
+        exit 1
+    }
+    cd ..
+done
+
+print -- "Create article"
+./create_ymd.sh > $webroot/latest.ymd
+
+print -- "Copy source codes"
+ycp() {
+    local precedent=""
+    for e in $*;do
+        [[ $precedent != "" ]] && print -- "\t$precedent"
+        precedent=$e
+    done
+    cp $*
+}
+latestArticleDir=$(ls -l $webroot/latest.ymd | perl -pi -e 's#.*/##; s#.md$##')
+for langue in en fr; do
+    dst="$webroot/output/Scratch/$langue/blog/$latestArticleDir/code"
+    [[ ! -d $dst ]] && mkdir -p $dst
+    ycp *.lhs(N) $dst
+    for dir in ??_*(N/); do
+        [[ ! -d $dst/$dir ]] && mkdir $dst/$dir
+        ycp $dir/*.{lhs,hs}(.N) $dst/$dir
+    done
+done
+print -- "\nRecompile"
+cd $webroot
+./tasks/recompile