some content and fonts

convert.sh

@@ -38,6 +38,8 @@ wait
 
 mkdir -p ./_site/css
 mkdir -p ./_site/js
+mkdir -p ./_site/fonts
 cp ./css/base.css ./_site/css/base.css
 cp ./js/main.js ./_site/js/main.js
 cp ./favicon.ico ./_site/favicon.ico
+cp ./fonts/* ./_site/fonts/

css/base.css

@@ -1 +1,49 @@
-/* Add your CSS here. */
+@font-face {
+    font-family: "bagnardregular";
+    src: url("/fonts/bagnard-webfont.woff2") format("woff2"),
+         url("/fonts/bagnard-webfont.woff") format("woff");
+    font-weight: normal;
+    font-style: normal;
+}
+
+@import url("https://fonts.googleapis.com/css2?family=Ubuntu+Mono&display=swap");
+
+html {
+    color: #404040;
+    background-color: gainsboro;
+    font-family: "bagnardregular", serif;
+}
+
+body {
+    margin: auto;
+    width: 60%;
+    max-width: 1000px;
+    min-width: 200px;
+}
+
+pre {
+    background-color: #404040;
+    border-color: black;
+    border-style: solid;
+    border-width: 0 0 1em 0;
+    border-radius: 0.5em;
+    color: gainsboro;
+    padding: 1em;
+}
+
+code {
+    font-family: "Ubuntu Mono", monospace;
+}
+
+@media (prefers-color-scheme: dark) {
+    html {
+        color: gainsboro;
+        background-color: #404040;
+    }
+
+    pre {
+        background-color: gainsboro;
+        border-color: white;
+        color: #404040;
+    }
+}

env

@@ -1,2 +1,2 @@
-export SITE_ROOT="/simple-site"
-export SITE_TITLE="Simple Site"
+export SITE_ROOT="/blog"
+export SITE_TITLE="Perfect5th 2.0"

markdown/haskell-aoc/day-1-1.md

@@ -0,0 +1,219 @@
+# An AoC Intro to Haskell - Day 1, Part 1
+
+## Last updated 2020-04-10
+
+[Back to AoC Intro to Haskell Index](./)
+
+## Intro
+
+[Day1, Part1][1] is *very* straightforward. We need to calculate the total fuel requirement to
+launch a series of modules, where the requirement for one module is:
+
+    fuel = max(mass // 3 - 2, 0)
+
+Where `mass` is the mass of the module and `//` is floor division (rounding down). We take the `max`
+of the result versus zero to ensure we don't get a negative fuel value.
+
+The best we can do here is O(n), as we need to do the calculation of each module. The input is the
+module weights, line-separated:
+
+    104451
+    112406
+    109733
+    ...
+
+## Iterative Approach
+
+A naive iterative approach, using Python 3 as an example, assuming our input has already been read
+into an array of integers called `ipt` (`input` is a builtin func in Python 3):
+
+    total = 0
+
+    for i in ipt:
+        total += max(i // 3 - 2, 0)
+
+## Functional (Python) Approach
+
+We can convert the above to a semi-functional approach while still using Python. This will help
+inform our pure functional Haskell solution:
+
+    total = sum(map(lambda i: max(i // 3 - 2, 0), ipt))
+
+I've used `map` here instead of a list comprehension because `map` returns a generator while a list
+comprehension produces a list. Not a huge performance gain, but the laziness better simulates
+Haskell (more on that later).
+
+## Haskell: Reading in the File
+
+The first thing I'm going to do is make the problem more complicated than it is treated above. File
+I/O in Python is old hat, so I omitted it, but I/O in Haskell is *interesting*. This is because
+Haskell is pure, and I/O is decidedly not.
+
+Practically, Haskell functions are separated into pure and impure. Pure ones are ones that are
+mathematical, deterministic, don't have side-effects, and *always return something* (technically
+only the side-effects part is necessary though). Having these properties is fantastic from a
+programming perspective, as it allows all sorts of great assumptions about correctness and
+optimizations.
+
+Impure functions are ones that have side-effects, can break, are possibly nondeterministic. I/O
+falls into this category. Therefore, any function in Haskell that uses I/O is automatically impure.
+If a function calls an impure function, it also becomes impure. The impurity "spreads", so it
+encourages the programmer to keep their impure functions separate from their pure functions as much
+as possible.
+
+Every Haskell program has a `main` function, which is decidedly impure, as, at the very first, it
+reads arguments from standard input.
+
+Enough manifesto – let's read a file:
+
+    main = do
+        rawInput <- readFile "input.txt" -- Read input file to String
+
+In main, we want to do three things:
+
+ 1. Read the input file (above)
+ 1. Parse it to a list of integer module weights
+ 1. Calculate the sum of the fuel values for those integers
+
+We use the `do` keyword because we want to do multiple things in which the order is important.
+
+The above accomplishes step 1. [`readFile`][2] has the function signature `FilePath -> IO String`.
+The `IO` part of `IO String` tells us that this is an "I/O monad" containing a `String`. We can talk
+more about monads later, but in this case, simply think of it as a wrapper that may contain a
+`String` or may contain an `IOError`. Functions are called by simply listing the name, then the
+arguments space-separated: `myFunc arg1 arg2 arg3`.
+
+`<-` optimistically unwraps the `IO String` to get at the `String` underneath, then binds it to the
+variable `rawInput`. If there was an I/O error, this is where it would crash.
+
+Anything that starts with `--` is a comment.
+
+So now we have a variable bound to a `String`, which contains our entire input file (we don't
+*really* have this, on account of laziness, but shush for now).
+
+## Haskell: Parsing the String
+
+Time for step 2 – we need to turn our `String` into a list of integers.
+
+*(Warning: I'm going to be doing the rest of this in a very obtuse way all within the `main`
+function. This is because I can illustrate the most concepts that way in the smallest amount of
+space.)*
+
+Let's (proactive pun) add another line to our `main`:
+
+    main = do
+        rawInput <- readFile "input.txt"
+        -- Parse the String to a list of Ints
+        let input = [read i :: Int | i <- lines rawInput] in
+            -- TODO
+            
+Looks weird, yeah? Here's the breakdown:
+
+`lines` is a function with a signature `String -> [String]`. That is, it takes a `String` and
+produces a list of `Strings` by splitting the original `String` on newline characters.
+
+Constructs of the form `[myFunc x | x <- myList]` are [list comprehensions][3]. Just like Python's
+comprehension, it takes a list to the right of the `<-` and an operation to the left of the `|` and
+applies the operation to each list item (bound to `x`) to produce a new list (just like `map`). The
+above in Python would look like `[myFunc(x) for x in myList]`.
+
+In the Python 3 version of this, I used `map` to attempt laziness via a Python generator. In
+Haskell, pretty much everything is lazy by default, and this applies to list comprehension.
+
+`read i :: Int` is a typecast, in a way. `read` is a funny Haskell function with the signature
+`Read a => String -> a` which means "given a type, `a` that is part of the `Read` typeclass (can be
+parsed), attempt to parse the given `String` to that type." Wordy, but more simply, "try to parse
+this `String` to an `Int`" in this concrete case.
+
+So, overall, `let input = [read i :: Int | i <- lines rawInput]` is a one-liner that splits our raw
+input into lines, parses each line to an `Int`, then binds that list of `Ints` to the variable
+`input`.
+
+Why does this binding use `let` instead of `<-` like the `readFile` one? Because this operation is
+(theoretically) pure – there's no `IO Monad` involved. [Let bindings][4] contextually bind a value
+to a variable name for the scope of their body (the `in` block).
+
+## Haskell: Finishing the Calculation
+
+All that's left now is to perform the actual calculation, which we'll do in the `let ... in` body
+using, you guess it, a list comprehension.
+
+Our final program (less the comments) is below:
+
+    main = do
+        rawInput <- readFile "input.txt"
+        let input = [read i :: Int | i <- lines rawInput] in
+            -- Perform the calculation and print result
+            print $ sum [max 0 $ quot i 3 - 2 | i <- input]
+
+Your first question is probably "`$`???", and we'll get to that.
+
+The list comprehension is the same as before, except we aren't doing any extra work on the right
+side of it, as we already have the input list we want.
+
+The operation is `max 0 $ quot i 3 - 2`, which is a mouthful. `quot` is a function with signature
+`a -> a -> a` that performs integer division, truncated towards zero (rounded down). This signature
+looks weird, and that's because Haskell functions only actually take a single argument. Ever. At
+least, that's how it's abstracted. So how can division occur, as obviously division requires two
+arguments? Simple: when given the first argument, `quot` returns a **curried** function with
+signature `a -> a`, which the second argument is given to. You'll get used to it.
+
+`quot i 3` takes `i` and divides it by 3, rounding down. Function application has really high
+precedence in Haskell, so the `quot i 3 - 2` can be read as `((quot i) 3) - 2)` in a kind of
+pseudo-Polish Notation, or `quot(i)(3) - 2` in a curried-function notation, or `quot(i, 3) - 2` in a
+more familiar C-style notation.
+
+Now we can talk about `max 0 $ quot i 3 - 2`. `max` is a function with signature
+`Ord a => a -> a -> a` – it consumes two arguments of the same type, `a`, that are of Typeclass
+`Ord`erable, and returns the maximum of the two. The `$` is [actually a function][5] (gasp! though
+it's probably actually a kind of macro) with the signature `(a -> b) -> a -> b`. It's an **infix**
+function, meaning it's first and second arguments are on either side of it. On the left, a function
+that takes an `a` and returns a `b` (note: these can be the same type, they just aren't guaranteed
+to be). `max 0` fits this bill, as `max`, with one argument applied, returns an `(a -> a)`. `$` then
+takes its right argument and applies it to the left argument.
+
+Why do all this work though? The main reason is code cleanliness. Without the `$`, `max 0 quot i 3`
+(I'm omitting the `- 2` for brevity) would be interpreted as `((max 0 quot) i 3)`, as function
+application has very high precedence. `$` evaluates its right argument first, *then* applies it to
+it's left argument, so `max 0 $ quot i 3` is instead interpreted `(max 0) (quot i 3)`, which could
+also be thought of as `(max 0 (quot i 3))`. Mentally, when you see a `$`, it's the same as replacing
+`$` with a `(` and adding a `)` at the end of the line. `max 0 $ quot i 3` becomes
+`max 0 (quot i 3)`.
+
+After our list comprehension is done, we have a list of all the fuel weights, and we apply that to
+`sum`, a function with signature `(Foldable t, Num a) => t a -> a`. Foldables are anything that can
+be "folded" into a single value, and Nums are numbers (obviously). `sum` folds our list into a
+single value by accumulating each element with `+`.
+
+`print` has the signature `Show a => a -> IO ()`. Typeclass Show includes any type that has a way to
+be displayed as a String. `IO ()` is an I/O Monad that doesn't contain anything. This is used
+because writing to standard out can still error, but if it succeeds, we don't expect a value back.
+We use `$` again so that `print` doesn't just try to `(print sum) ...`, which would be pretty
+useless.
+
+## Haskell: Final Program
+
+I can confirm that our final program:
+
+    main = do
+        rawInput <- readFile "input.txt"
+        let input = [read i :: Int | i <- lines rawInput] in
+            print $ sum [max 0 $ quot i 3 - 2 | i <- input]
+
+Nets me the correct solution for Day 1, Part 1. It's not pretty, but that wasn't the point.
+Obviously this could be refactored to use separate functions, and `map` could be used instead of
+list comprehensions if you like that style.
+
+    $ runhaskell day-1-1.hs
+    3538016
+
+Eventually, [Day 1, Part 2](./day-1-2.html) will adapt this code further, and introduce a little
+recursion for funsies.
+
+— Mitch
+
+   [1]: https://adventofcode.com/2019/day/1 "Advent of Code 2019, Day 1"
+   [2]: https://hackage.haskell.org/package/base-4.12.0.0/docs/Prelude.html#v:readFile "Haskell readFile documentation"
+   [3]: https://learnyouahaskell.com/starting-out#im-a-list-comprehension "Learn You a Haskell: list comprehensions"
+   [4]: https://learnyouahaskell.com/syntax-in-functions#let-it-be "Learn You a Haskell: let bindings"
+   [5]: http://learnyouahaskell.com/higher-order-functions#function-application "Learn You a Haskell: function application"

markdown/haskell-aoc/index.md

@@ -0,0 +1,24 @@
+# An AoC Intro to Haskell
+
+## Last updated 2020-04-14
+
+This may sound obvious, but I think one of the best ways to learn a programming language is to solve
+problems with it. This works well when they are problems that you know you could solve in a language
+you are more familiar with. That way, you spend most of your energy on the translation and less on
+the problem solving.
+
+To that end, I've decided to work through the [2019 Advent of Code][1] using Haskell, explaining
+what I'm doing as I go. Let's see how far I manage to get before other things draw me away, or I
+feel like it's no longer productive.
+
+Most of these problems I've already solved in Python, C (urgh), or C++, so I'll more or less be
+trying to translate my solutions and referring to them a bit. Let's go!
+
+ - Day 1
+   - [Part 1](day-1-1.html)
+   - [Part 2](day-1-2.html)
+ - Day 2
+   - [Part 1](day-2-1.html)
+   - [Part 2](day-2-2.html)
+
+   [1]: https://adventofcode.com/2019/ "Advent of Code 2019"

markdown/index.md

@@ -1,9 +1,16 @@
-# Simple Site
+# Perfect5th, 2.0
 
-Welcome to the homepage! You're on the demo site for my *very* simple markdown-based
-static site generator. Check out [the GitHub repo][github repo].
+Hiya! I'm not sure what I'm actually going to use this site for, but it seems like a decent alt
+to [my personal site][1], where I can dump less-structured content, TILs, and other faffery.
 
-There's a subpage [here][1].
+This site is based on [Simple Site][2], a very simple (*i.e.*, single `sh` script-based) static
+site generator that turns markdown into HTML. I didn't really want or need anything fancy for this,
+and producing this tool seemed like an easy way to get rid of a lot of cruft.
 
-   [1]: subpage "A test subpage"
-   [github repo]: https://github.com/perfect5th/simple-site "Simple Site GitHub Repo"
+Feeling cute, might add RSS one day, here's an index of top-level pages that I've migrated from the
+personal wiki I used to maintain.
+
+ - [An AoC Intro to Haskell](haskell-aoc)
+
+   [1]: https://mitchellburton.ca
+   [2]: https://github.com/perfect5th/simple-site "Simple Site GitHub Repo"