Rewrite IHaskell tutorial.

IHaskell/examples/tutorial-ihaskell-inline-r.ipynb

@@ -0,0 +1,246 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Programming R from Haskell"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This notebook demonstrates integrating both R and Haskell in the same notebook, using `IHaskell-inline-r`."
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Prelude"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "First, a bit of setup. We need to enable quasiquotation, to embed R code into Haskell expressions:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    ":ext QuasiQuotes"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Next, we need to make sure that R is initialized properly:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "import qualified H.Prelude as H\n",
+    "initializeEmbeddedR defaultConfig"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## R computations"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "By default, computations in code cells are interpreted as Haskell code. For instance, here is a definition of the factorial function, in Haskell:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": true
+   },
+   "outputs": [],
+   "source": [
+    "fact 0 = 1\n",
+    "fact n = n * fact (n - 1)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Here is a Haskell expression calling `fact`, together with its value:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "fact 10"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "`inline-r` allows you to embed R expressions and R statements anywhere in Haskell code, using quasiquotation. The following is an IO action that asks R to print the value of the R code snipped embedded between the brackets:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[rprint| 1 + 1 |]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "You can define the factorial function using R code, just as you can using Haskell code, so long as the R code is delineated within a quasiquote:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[r| fact <- function(n) if(n == 0) 1 else n * fact(n - 1) |]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The `r` quasiquote is used for embedding R code that is only useful for its side effects. This is the case with the code above which has the side effect of binding `fact` in the toplevel environment. Applying the definition:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[rprint| fact(10) |]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## R graphics"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "R has extremely powerful plotting facilities. They are available out-of-the-box:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[rgraph| plot(cars) |]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "For effect, we can fit a straight line through our data set:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[rgraph| plot(cars); abline(lm(cars$dist ~ cars$speed), col=\"red\") |]"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "R code snippets that have graphical output should be embedded using the `rgraph` quasiquote. The other quasiquotes ignore graphical output. For a more complex example, consider the following density plot (requires `ggplot2` to be installed):"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[r| require(\"ggplot2\") |]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {
+    "collapsed": false
+   },
+   "outputs": [],
+   "source": [
+    "[rgraph|\n",
+    "  Xv <- c(rnorm (500, 10,3), rnorm (500, 50, 20), rnorm (500, 70, 20))\n",
+    "  Yv <- c(rnorm (500, 10,3), rnorm (500, 70, 5), rnorm (500, 30, 5))\n",
+    "  myd <- data.frame(Xv, Yv)\n",
+    "\n",
+    "  ggplot(myd, aes(x = Xv, y = Yv)) + geom_point() + geom_density2d() + theme_bw() |]"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Haskell",
+   "language": "haskell",
+   "name": "haskell"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 0
+}