wip

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

@@ -1,6 +1,18 @@
 /* Generated by pandoc. */
-table.sourceCode, tr.sourceCode, td.lineNumbers, td.sourceCode, table.sourceCode pre
+table.sourceCode, tr.sourceCode, td.lineNumbers, td.sourceCode, table.sourceCode pre.sourceCode
-   { margin: 0; padding: 0; border: 0; vertical-align: baseline; border: none; }
+{
+  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; }

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

site.hs

@@ -1,9 +1,7 @@
---------------------------------------------------------------------------------
 {-# 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)
 
 
 --------------------------------------------------------------------------------
@@ -31,34 +29,20 @@ main = hakyllWith defaultConfiguration{ deployCommand = "ipfs add -Q -r _site" }
             >>= loadAndApplyTemplate "templates/default.html" defaultContext
             >>= relativizeUrls
 
-    match "posts/incomplete/*" $ do
+    match "posts/*" $ do
       route $ setExtension "html"
       compile $ pandocCompiler
         >>= loadAndApplyTemplate "templates/post.html"    postCtx
         >>= loadAndApplyTemplate "templates/default.html" postCtx
         >>= relativizeUrls
 
-    match "posts/guides/*" $ do
+    create ["posts.html"] $ do
-      route $ setExtension "html"
-      compile $ pandocCompiler
-        >>= loadAndApplyTemplate "templates/post.html"    postCtx
-        >>= loadAndApplyTemplate "templates/default.html" postCtx
-        >>= relativizeUrls
-
-    match "posts/brainstorming/*" $ 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 ""
@@ -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

@@ -18,6 +18,7 @@
                 <!-- Logo by Jason Long -->
                 <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>
 

templates/guides.html

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