wip

.gitignore

@@ -1,2 +1,3 @@
-_site
+_site/
-_cache
+_cache/
+dist/

LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2018, Mats Rauhala
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Mats Rauhala nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

about.markdown

@@ -1,29 +0,0 @@
----
-title: About
----
-
-![](./images/profile.jpg)
-
-I'm a software developer from southern Finland. I'm currently working as a
-Haskell developer at Relex Oy involved in an internal tool. I also have
-experience with systems integrations and backend web development.
-
-I'm also an aviation enthusiast. I have a glider pilots license and a touring
-motor glider pilots license (LAPL(S)+TMG).
-
-My [GPG key](./resources/2104943D6033C.txt)
-
-### Notable experience and interests
-
-- **Haskell**
-    - Working on an internal Haskell based tool at Relex Oy
-    - Some contributions to [darcshub](https://hub.darcs.net/)
-    - Some contributions to [xmonad](https://github.com/xmonad)
-    - Dozens of personal projects, most of which ended up being just tests for
-      different libraries, techniques or algorithms.
-- **Systems integrations**
-    - Working as a consultant from Avoltus Oy to different companies using
-      [Mulesoft](https://developer.mulesoft.com/). Systems include webshops,
-      different databases, crms and erps.
-- **Java**
-    - Bunch of different smaller projects while working at Avoltus Oy

css/default.css

@@ -111,7 +111,7 @@ article .header {
 
 @media (min-width: 640px) {
   body {
-    width: 60rem;
+    width: 85rem;
     margin: 0 auto;
     padding: 0;
   }

css/highlight.css

@@ -0,0 +1,30 @@
+/* Generated by pandoc. */
+table.sourceCode, tr.sourceCode, td.lineNumbers, td.sourceCode, table.sourceCode pre.sourceCode
+{
+  margin: 0;
+  padding: 0;
+  /* border: 0; */
+  vertical-align: baseline;
+}
+pre.sourceCode
+{
+  border: 1px solid #ccc;
+  background-color: rgb(238,238,255);
+  padding: 10px;
+  overflow: auto;
+}
+td.lineNumbers { border-right: 1px solid #AAAAAA; text-align: right; color: #AAAAAA; padding-right: 5px; padding-left: 5px; }
+td.sourceCode { padding-left: 5px; }
+.sourceCode span.kw { color: #007020; font-weight: bold; }
+.sourceCode span.dt { color: #902000; }
+.sourceCode span.dv { color: #40a070; }
+.sourceCode span.bn { color: #40a070; }
+.sourceCode span.fl { color: #40a070; }
+.sourceCode span.ch { color: #4070a0; }
+.sourceCode span.st { color: #4070a0; }
+.sourceCode span.co { color: #60a0b0; font-style: italic; }
+.sourceCode span.ot { color: #007020; }
+.sourceCode span.al { color: red; font-weight: bold; }
+.sourceCode span.fu { color: #06287e; }
+.sourceCode span.re { }
+.sourceCode span.er { color: red; font-weight: bold; }

default.nix

@@ -1,3 +1,3 @@
-{ haskellPackages }:
+{ haskellPackages, haskell }:
 
-haskellPackages.callCabal2nix "site" ./. {}
+haskell.lib.disableSharedExecutables (haskellPackages.callCabal2nix "site" ./. {})

index.html

@@ -1,7 +0,0 @@
----
-title: Home
----
-
-<h2>Welcome</h2>
-
-<p>Not much here yet. See the top bar</p>

index.markdown

@@ -0,0 +1,31 @@
+---
+title: Mats Rauhala
+---
+
+![](./images/profile.jpg)
+
+I'm a software developer from southern Finland. I'm currently working as a
+Haskell developer at Relex Oy involved in an internal tool. I also have
+experience with systems integrations and backend web development.
+
+I'm also an aviation enthusiast. I have a glider pilots license and a touring
+motor glider pilots license (LAPL(S)+TMG).
+
+My [GPG key](./resources/2104943D6033C.txt)
+
+### Notable experience and interests
+
+- **Haskell**
+  - Working on an internal Haskell based tool at Relex Oy
+  - Some contributions to [darcshub](https://hub.darcs.net/)
+  - Some contributions to [xmonad](https://github.com/xmonad)
+  - Dozens of personal projects, most of which ended up being just tests for
+    different libraries, techniques or algorithms.
+- **Systems integrations**
+  - Working as a consultant from Avoltus Oy to different companies using
+    [Mulesoft](https://developer.mulesoft.com/). Systems include webshops,
+    different databases, CRMs and ERPs.
+- **Java**
+  - Bunch of different smaller projects while working at Avoltus Oy.
+- **Other**
+  - I was involved in creating an email solicit platform.

js/api.js

@@ -0,0 +1,22 @@
+
+var getApiIpfsCurrent = function(onSuccess, onError) {
+  var xhr = new XMLHttpRequest();
+  xhr.open('GET', '/api/ipfs/current', true);
+  xhr.setRequestHeader('Accept', 'application/json');
+  xhr.onreadystatechange = function () {
+    var res = null;
+    if (xhr.readyState === 4) {
+      if (xhr.status === 204 || xhr.status === 205) {
+        onSuccess();
+      } else if (xhr.status >= 200 && xhr.status < 300) {
+        try { res = JSON.parse(xhr.responseText); } catch (e) { onError(e); }
+        if (res) onSuccess(res);
+      } else {
+        try { res = JSON.parse(xhr.responseText); } catch (e) { onError(e); }
+        if (res) onError(res);
+      }
+    }
+  };
+  xhr.send(null);
+};
+

js/app.js

@@ -0,0 +1,10 @@
+$(document).ready(function() {
+    var success = function(x) {
+	$("#ipfs > em").html(x);
+    };
+    var error = function(x) {
+	$("#ipfs").hide();
+	console.log("ipfs hash not found: " + x);
+    };
+    getApiIpfsCurrent(success, error);
+});

posts/configs.md

@@ -0,0 +1,78 @@
+---
+title: Extensible configuration Pt. 1
+date: 2019-03-27
+---
+
+This is the first part of a series where I'm going through how to make
+extensible configuration. There is nothing groundbreaking or new in this
+series, it's just me going through different implementations and trying to
+understand them.
+
+The source material for this post is [the fixed point implementation](https://github.com/NixOS/nixpkgs/blob/master/lib/fixed-points.nix) for nix.
+
+By extensible configuration, I'm talking about nix style extensible
+configuration, like overlays, overrides and extensions. Let's see an example of
+an extensible configuration.
+
+``` nix
+{ haskellPackages, fetchFromGitHub }:
+
+let
+  purescript = fetchFromGitHub {
+    owner = "purescript";
+    repo = "purescript";
+    rev = "2cb4a6496052db726e099539be682b87585af494";
+    sha256 = "1v4gs08xnqgym6jj3drkzbic7ln3hfmflpbpij3qzwxsmqd2abr7";
+  }
+  hp = haskellPackages.extend (self: super: {
+    purescript = super.callCabal2nix "purescript" purescript {};
+  });
+
+in
+
+hp.purescript;
+```
+
+On a high level we are augmenting the `haskellPackages` attrset by replacing
+the existing purescript package with a different one. The extension is a
+function that takes two arguments, `self` and `super`. `super` is the original
+non-lazy value and `self` is the lazy value that corresponds to the value at
+end.
+
+The first step on this journey is done by getting to know `fix`. Fix is
+described being the least fixed point of a function. In practice it's a
+function allowing declaring recursive functions without explicit recursion.
+
+``` nix
+fix = f: let x = f x; in x
+```
+
+With fix you can have access to the lazy `self` value. It's value is whatever
+would have been computed in the end. As it is lazy, it is possible to end up in
+a recursive loop if there is a cyclic dependency.
+
+``` nix
+let recursive = fix (self: {
+  foo = 3;
+  bar = self.foo + 1;
+});
+infinite = fix (self: {
+  foo = self.bar + 1;
+  bar = self.foo + 1;
+});
+```
+
+You can try those yourself. The first version is fine and returns an attrset
+like you would expect. The second one has a cyclic dependency and nix helpfully
+errors out.
+
+The next step is making a function that has access to the unmodified original
+values. This is managed through the `extends` function. It took a while for me to understand what's happening in there, but luckily nix has [good documentation](https://github.com/NixOS/nixpkgs/blob/67b1265fb3d38ead5a57fee838405a2d997777c2/lib/fixed-points.nix#L37-L65) for it.
+
+``` nix
+extends = f: rattrs: self: let super = rattrs self; in super // f self super
+```
+
+- https://elvishjerricco.github.io/2017/04/01/nix-style-configs-in-haskell.html
+- https://github.com/NixOS/nixpkgs/blob/master/lib/fixed-points.nix
+- https://chshersh.github.io/posts/2019-03-25-comonadic-builders

posts/demobot.md

@@ -0,0 +1,148 @@
+---
+title: Functional architecture Pt. 1
+date: 2018-12-25
+---
+
+
+I'm lucky enough to work with Haskell professionally which gives me some view
+to good and maintainable real world architecture. In my opinion, one of the
+biggest contributing factors to how your general architecture is defined, is
+determined by the base application monad stack you are using.
+
+Our actual product is mostly in the regular `LoggingT (ReaderT app IO)` base
+monad with whatever style you would imagine with that base monad in place. It's
+not entirely consistent, but close enough.
+
+With all the talk about just having `IO`, `ReaderT app IO`, free monads or
+tagless final monads, I thought of trying different styles. For this post I'm
+focusing on the tagless final since it's most interesting for me right now.
+
+`IO`
+
+:   The most basic style. This is pretty much only suitable for the most basic
+of needs.
+
+`ReaderT app IO`
+
+:   How we mostly define the base monad. This is a really good way of doing
+things, it gives you a lot of leeway on how you can define the rest of your
+application.
+
+`Free monads`
+
+:   Free monads are a way of having a small constrained DSL or monad stack for
+defining your application. By constraining the user, you are also reducing the
+area for bugs. There is also some possibility for introspection, but usually
+this isn't a usable feature. Also since free monad applications need the full
+AST, they're quite a bit slower than the other solutions.
+
+`Tagless final`
+
+:   This is something I'm the least familiar with. If I have understood
+correctly, free monads and tagless final are more or less equivalent solutions
+in their power, but in tagless final you aren't creating the AST anywhere,
+which also means that you aren't paying for it either.
+
+That out of the way, I had a small project idea for a bot that's easy to
+contribute to, difficult to make errors and easy to reason about. The project
+is at most a proof-of-concept and most definitely not production quality.
+Still, I hope it's complex enough to showcase the architecture.
+
+The full source code is available [at my git repository](https://git.rauhala.info/MasseR/demobot).
+
+For the architecture to make sense, let me introduce two different actors: a
+*core contributor* that's familiar with Haskell and a *external contributor*
+that's familiar with programming, not necessarily with Haskell.
+
+The repository is split into two parts, the library and the application.
+
+The library
+
+:   Provides the restricted monad classes (tagless final), extension points and
+the core bot main loop.
+
+The application
+
+:   Provides the implementation for the tagless final type classes, meaning
+that the application defines how the networking stack is handled, how database
+connectivity is done and so on. It also collects all the extensions for that
+specific application.
+
+The *core contributor* is responsible for maintaining the library as well as
+the type class instances for the application type. The *external contributor*
+is responsible for maintaining one or multiple extensions that are restricted
+in their capability and complexity.
+
+I'm restricting the capabilities of the monad in the library and extensions,
+meaning that I'm not allowing any IO. For example the networking is handled by
+a single `MonadNetwork` type class. This is the most complex type class in the
+library right now, using type families for defining a specific extension point
+for the messages. This could be something like 'event type' for Flowdock
+messages or 'source channel' for IRC messages.
+
+~~~haskell
+data Request meta = Request { content :: Text
+                            , meta    :: meta }
+data Response meta = Response { content :: Text
+                              , meta    :: meta }
+
+class Monad m => MonadNetwork m where
+  type Meta m :: *
+  recvMsg :: m (Request (Meta m))
+  putMsg :: Response (Meta m) -> m ()
+~~~
+
+Then we have the extension point which is more or less just a `Request -> m (Maybe Response)`. I'm using rank n types here for qualifying the `Meta`
+extension point and forcing the allowed type classes to be a subset of the
+application monad stack, I don't want extension writers to be able to write
+messages to the bot network by themselves.
+
+~~~haskell
+data Extension meta =
+  Extension { act :: forall m. (meta ~ Meta m, MonadExtension m) => Request meta -> m (Maybe (Response meta))
+            , name   :: String }
+~~~
+
+Last part of the library is the main loop, which is basically a free monad
+(tagless final) waiting for an interpreter. At least in this POC I find this
+style to be really good, it's really simplified, easy to read and hides a lot
+of the complexity, while bringing forth the core algorithm.
+
+~~~haskell
+mainLoop :: forall m. (MonadCatch m, MonadBot m) => [Extension (Meta m)] -> m ()
+mainLoop extensions = forever $ catch go handleFail
+  where
+    handleFail :: SomeException -> m ()
+    handleFail e = logError $ tshow e
+    go :: m ()
+    go = do
+      msg <- recvMsg
+      responses <- catMaybes <$> mapM (`act` msg) extensions
+      mapM_ putMsg responses
+~~~
+
+Then comes the actual application where we write the effectful interpreters. In
+this POC the interpreter is just a `LoggingT IO a` with the semantics of
+stdin/stdout. This is the only file where we're actually interacting with the
+outside world, everything else is just pure code.
+
+~~~haskell
+instance MonadNetwork AppM where
+  type Meta AppM = ()
+  recvMsg = Request <$> liftIO T.getLine <*> pure ()
+  putMsg Response{..} = liftIO . T.putStrLn $ content
+~~~
+
+Writing the extensions was the responsibility of *external contributors* and we
+already saw how the actual extension point was defined above. Using these
+extension points is really simple and here we see how the implementation is
+just a simple `Request -> m (Maybe Response)`.
+
+~~~haskell
+extension :: Extension ()
+extension = Extension{..}
+  where
+    name = "hello world"
+    act Request{..} | "hello" `T.isPrefixOf` content = return $ Just $ Response "Hello to you" ()
+                    | otherwise = return Nothing
+~~~

site.cabal

@@ -2,11 +2,15 @@ name:               site
 version:            0.1.0.0
 build-type:         Simple
 cabal-version:      >= 1.10
+license:            BSD3
+license-file:       LICENSE
+author:             Mats Rauhala
+maintainer:         mats.rauhala@iki.fi
 
 executable site
   main-is:          site.hs
   build-depends:    base == 4.*
-                  , hakyll == 4.10.*
+                  , hakyll >= 4.10
                   , time
   ghc-options:      -threaded
   default-language: Haskell2010

site.hs

@@ -1,14 +1,12 @@
---------------------------------------------------------------------------------
 {-# LANGUAGE OverloadedStrings #-}
-import           Data.Monoid (mappend)
+import           Data.List   (sortOn)
+import           Data.Time   (defaultTimeLocale, formatTime)
 import           Hakyll
-import           Data.List (sortBy, sortOn)
-import           Data.Time (formatTime, defaultTimeLocale)
 
 
 --------------------------------------------------------------------------------
 main :: IO ()
-main = hakyll $ do
+main = hakyllWith defaultConfiguration{ deployCommand = "ipfs add -Q -r _site" } $do
     match "images/*" $ do
         route   idRoute
         compile copyFileCompiler
@@ -21,33 +19,30 @@ main = hakyll $ do
         route   idRoute
         compile compressCssCompiler
 
-    match (fromList ["about.markdown", "contact.markdown"]) $ do
+    match "js/*" $ do
+        route   idRoute
+        compile compressCssCompiler
+
+    match (fromList ["index.markdown", "contact.markdown"]) $ do
         route   $ setExtension "html"
         compile $ pandocCompiler
             >>= loadAndApplyTemplate "templates/default.html" defaultContext
             >>= relativizeUrls
 
-    match "posts/guides/*" $ do
+    match "posts/*" $ do
       route $ setExtension "html"
       compile $ pandocCompiler
         >>= loadAndApplyTemplate "templates/post.html"    postCtx
         >>= loadAndApplyTemplate "templates/default.html" postCtx
         >>= relativizeUrls
 
-    match "posts/brainstorming/*" $ do
+    create ["posts.html"] $ do
-      route $ setExtension "html"
-      compile $ pandocCompiler
-        >>= loadAndApplyTemplate "templates/post.html"    postCtx
-        >>= loadAndApplyTemplate "templates/default.html" postCtx
-        >>= relativizeUrls
-
-    create ["guides.html"] $ do
         route idRoute
         compile $ do
-            posts <- modFirst =<< loadAll "posts/guides/*"
+            posts <- modFirst =<< loadAll "posts/*"
             let archiveCtx =
-                    listField "posts" postCtx (return posts) `mappend`
+                    listField "posts" postCtx (return posts) <>
-                    constField "title" "Guides"            `mappend`
+                    constField "title" "Posts"               <>
                     defaultContext
 
             makeItem ""
@@ -55,17 +50,6 @@ main = hakyll $ do
                 >>= loadAndApplyTemplate "templates/default.html" archiveCtx
                 >>= relativizeUrls
 
-    match "index.html" $ do
-        route idRoute
-        compile $ do
-            let indexCtx =
-                    constField "title" "Home"                `mappend`
-                    defaultContext
-
-            getResourceBody
-                >>= applyAsTemplate indexCtx
-                >>= loadAndApplyTemplate "templates/default.html" indexCtx
-                >>= relativizeUrls
 
     match "templates/*" $ compile templateBodyCompiler
 
@@ -78,8 +62,8 @@ modFirst = fmap reverse . modified
 --------------------------------------------------------------------------------
 postCtx :: Context String
 postCtx =
-    dateField "date" "%B %e, %Y" `mappend`
+    dateField "date" "%B %e, %Y" <>
-    modifiedField "modified" "%B %e, %Y" `mappend`
+    modifiedField "modified" "%B %e, %Y" <>
     defaultContext
   where
     modifiedField key format = field key $ \i -> do

templates/default.html

@@ -6,6 +6,7 @@
         <meta name="viewport" content="width=device-width, initial-scale=1">
         <title>rauhala.info - $title$</title>
         <link rel="stylesheet" href="/css/default.css" />
+        <link rel="stylesheet" href="/css/highlight.css">
     </head>
     <body>
         <header>
@@ -13,10 +14,11 @@
                 <a href="/">rauhala.info</a>
             </div>
             <nav>
-                <a href="/">Home</a>
+                <!-- Git logo from https://git-scm.com/downloads/logos -->
-                <a href="/guides.html">Guides</a>
+                <!-- Logo by Jason Long -->
-                <a href="/about.html">About</a>
+                <a href="https://git.rauhala.info"><img src="/images/git_16.png" alt="git" /></a>
                 <a href="/contact.html">Contact</a>
+                <a href="/posts.html">Posts</a>
             </nav>
         </header>
 
@@ -28,6 +30,10 @@
         <footer>
             Site proudly generated by
             <a href="http://jaspervdj.be/hakyll">Hakyll</a>
+            <span id="ipfs">and found on IPFS as <em></em></ipfs>
         </footer>
     </body>
+    <script type="application/javascript" src="/js/jquery-3.3.1.min.js"></script>
+    <script type="application/javascript" src="/js/api.js"></script>
+    <script type="application/javascript" src="/js/app.js"></script>
 </html>

templates/guides.html

@@ -1,3 +1,3 @@
-A list of small and big guides.
+Me writing out interesting ideas and experiments.
 
 $partial("templates/post-list.html")$

templates/post-list.html

@@ -1,7 +1,7 @@
 <ul>
     $for(posts)$
         <li>
-            <a href="$url$">$title$</a> - $date$
+            <a href="$url$">$title$</a> - $modified$
         </li>
     $endfor$
 </ul>