-
Notifications
You must be signed in to change notification settings - Fork 0
/
talk-immutability-pure-functions.html
738 lines (690 loc) · 46.8 KB
/
talk-immutability-pure-functions.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="generator" content="pandoc">
<meta name="author" content="Malte Neuss">
<title>Immutability & Pure Functions</title>
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, minimal-ui">
<link rel="stylesheet" href="https://unpkg.com/reveal.js@^4//dist/reset.css">
<link rel="stylesheet" href="https://unpkg.com/reveal.js@^4//dist/reveal.css">
<style>
.reveal .sourceCode { /* see #7635 */
overflow: visible;
}
code{white-space: pre-wrap;}
span.smallcaps{font-variant: small-caps;}
span.underline{text-decoration: underline;}
div.column{display: inline-block; vertical-align: top; width: 50%;}
div.hanging-indent{margin-left: 1.5em; text-indent: -1.5em;}
ul.task-list{list-style: none;}
pre > code.sourceCode { white-space: pre; position: relative; }
pre > code.sourceCode > span { display: inline-block; line-height: 1.25; }
pre > code.sourceCode > span:empty { height: 1.2em; }
.sourceCode { overflow: visible; }
code.sourceCode > span { color: inherit; text-decoration: inherit; }
div.sourceCode { margin: 1em 0; }
pre.sourceCode { margin: 0; }
@media screen {
div.sourceCode { overflow: auto; }
}
@media print {
pre > code.sourceCode { white-space: pre-wrap; }
pre > code.sourceCode > span { text-indent: -5em; padding-left: 5em; }
}
pre.numberSource code
{ counter-reset: source-line 0; }
pre.numberSource code > span
{ position: relative; left: -4em; counter-increment: source-line; }
pre.numberSource code > span > a:first-child::before
{ content: counter(source-line);
position: relative; left: -1em; text-align: right; vertical-align: baseline;
border: none; display: inline-block;
-webkit-touch-callout: none; -webkit-user-select: none;
-khtml-user-select: none; -moz-user-select: none;
-ms-user-select: none; user-select: none;
padding: 0 4px; width: 4em;
color: #aaaaaa;
}
pre.numberSource { margin-left: 3em; border-left: 1px solid #aaaaaa; padding-left: 4px; }
div.sourceCode
{ }
@media screen {
pre > code.sourceCode > span > a:first-child::before { text-decoration: underline; }
}
code span.al { color: #ff0000; font-weight: bold; } /* Alert */
code span.an { color: #60a0b0; font-weight: bold; font-style: italic; } /* Annotation */
code span.at { color: #7d9029; } /* Attribute */
code span.bn { color: #40a070; } /* BaseN */
code span.bu { color: #008000; } /* BuiltIn */
code span.cf { color: #007020; font-weight: bold; } /* ControlFlow */
code span.ch { color: #4070a0; } /* Char */
code span.cn { color: #880000; } /* Constant */
code span.co { color: #60a0b0; font-style: italic; } /* Comment */
code span.cv { color: #60a0b0; font-weight: bold; font-style: italic; } /* CommentVar */
code span.do { color: #ba2121; font-style: italic; } /* Documentation */
code span.dt { color: #902000; } /* DataType */
code span.dv { color: #40a070; } /* DecVal */
code span.er { color: #ff0000; font-weight: bold; } /* Error */
code span.ex { } /* Extension */
code span.fl { color: #40a070; } /* Float */
code span.fu { color: #06287e; } /* Function */
code span.im { color: #008000; font-weight: bold; } /* Import */
code span.in { color: #60a0b0; font-weight: bold; font-style: italic; } /* Information */
code span.kw { color: #007020; font-weight: bold; } /* Keyword */
code span.op { color: #666666; } /* Operator */
code span.ot { color: #007020; } /* Other */
code span.pp { color: #bc7a00; } /* Preprocessor */
code span.sc { color: #4070a0; } /* SpecialChar */
code span.ss { color: #bb6688; } /* SpecialString */
code span.st { color: #4070a0; } /* String */
code span.va { color: #19177c; } /* Variable */
code span.vs { color: #4070a0; } /* VerbatimString */
code span.wa { color: #60a0b0; font-weight: bold; font-style: italic; } /* Warning */
</style>
<link rel="stylesheet" href="https://unpkg.com/reveal.js@^4//dist/theme/sky.css" id="theme">
<script defer=""
src="https://cdn.jsdelivr.net/npm/[email protected]/dist/katex.min.js"></script>
<script>document.addEventListener("DOMContentLoaded", function () {
var mathElements = document.getElementsByClassName("math");
var macros = [];
for (var i = 0; i < mathElements.length; i++) {
var texText = mathElements[i].firstChild;
if (mathElements[i].tagName == "SPAN") {
katex.render(texText.data, mathElements[i], {
displayMode: mathElements[i].classList.contains('display'),
throwOnError: false,
macros: macros,
fleqn: false
});
}}});
</script>
<link rel="stylesheet"
href="https://cdn.jsdelivr.net/npm/[email protected]/dist/katex.min.css" />
</head>
<body>
<div class="reveal">
<div class="slides">
<section id="title-slide">
<h1 class="title">Immutability & Pure Functions</h1>
<p class="author">Malte Neuss</p>
</section>
<section id="reasoning-about-code" class="slide level2">
<h2>Reasoning about code</h2>
<div class="sourceCode" id="cb1"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main()</span>
<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a> prices <span class="op">=</span> [<span class="dv">5</span>,<span class="dv">2</span>,<span class="dv">7</span>]</span>
<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb2"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a> minPrice <span class="op">=</span> minimum(prices)</span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert minPrice == 2</span></span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb3"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5?</span></span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb4"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> minimum(values)</span>
<span id="cb4-2"><a href="#cb4-2" aria-hidden="true" tabindex="-1"></a> values.sort() <span class="co"># surprise</span></span>
<span id="cb4-3"><a href="#cb4-3" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> values[<span class="dv">0</span>]</span></code></pre></div>
</div>
</section>
<section id="content" class="slide level2">
<h2>Content</h2>
<div>
<ul>
<li class="fragment">Immutability</li>
<li class="fragment">Pure Functions</li>
<li class="fragment">Apply to OO</li>
</ul>
</div>
<div class="fragment">
<blockquote>
<p><em>Easier reasoning, testing, debugging..</em></p>
</blockquote>
</div>
</section>
<section id="immutability" class="slide level2">
<h2>Immutability</h2>
<p>No reassign of variables:</p>
<div class="sourceCode" id="cb5"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a> value <span class="op">=</span> <span class="dv">1</span> <span class="co"># Assign</span></span>
<span id="cb5-2"><a href="#cb5-2" aria-hidden="true" tabindex="-1"></a><span class="co"># value = 2 # Reassign</span></span>
<span id="cb5-3"><a href="#cb5-3" aria-hidden="true" tabindex="-1"></a> other <span class="op">=</span> <span class="dv">2</span></span></code></pre></div>
<div class="fragment">
<p>No mutation on objects:</p>
<div class="sourceCode" id="cb6"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> minimum(values)</span>
<span id="cb6-2"><a href="#cb6-2" aria-hidden="true" tabindex="-1"></a> <span class="co"># values.sort() # mutation</span></span>
<span id="cb6-3"><a href="#cb6-3" aria-hidden="true" tabindex="-1"></a> other <span class="op">=</span> <span class="bu">sorted</span>(values) <span class="co"># no mutation</span></span>
<span id="cb6-4"><a href="#cb6-4" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> other[<span class="dv">0</span>]</span></code></pre></div>
</div>
</section>
<section id="benefit-reasoning" class="slide level2">
<h2>Benefit: Reasoning</h2>
<div class="sourceCode" id="cb7"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main()</span>
<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a> prices <span class="op">=</span> immutable([<span class="dv">5</span>,<span class="dv">2</span>,<span class="dv">7</span>]) <span class="co"># if supported</span></span>
<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5 </span></span>
<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a> minPrice <span class="op">=</span> minimum(prices)</span>
<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5! </span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb8"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> minimum(values)</span>
<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a> values.sort() <span class="co"># error</span></span>
<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> other[<span class="dv">0</span>]</span></code></pre></div>
</div>
</section>
<section id="pure-functions" class="slide level2">
<h2>Pure Functions</h2>
<p><span class="math display">
\begin{align*}
f\colon \mathbb{R} &\to \mathbb{R} \qquad &\text{Type} \\
f(x) &= x + \pi \qquad &\text{Body}
\end{align*}
</span></p>
<div class="fragment">
<div class="sourceCode" id="cb9"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb9-1"><a href="#cb9-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> f(x: <span class="bu">float</span>) <span class="op">-></span> <span class="bu">float</span>: <span class="co"># Type</span></span>
<span id="cb9-2"><a href="#cb9-2" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> x <span class="op">+</span> math.pi <span class="co"># Body</span></span></code></pre></div>
<div>
<ul>
<li class="fragment">Same input, same output</li>
<li class="fragment">No side-effects</li>
<li class="fragment">External immutable values or constants ok</li>
</ul>
</div>
</div>
</section>
<section id="side-effect" class="slide level2">
<h2>Side-Effect</h2>
<div>
<ul>
<li class="fragment">File read/write</li>
<li class="fragment">Network access</li>
<li class="fragment">I/O</li>
<li class="fragment">Throwing exception</li>
<li class="fragment">Argument mutation</li>
<li class="fragment">…</li>
</ul>
</div>
<div class="fragment">
<blockquote>
<p><em>Any state change outside of return value</em></p>
</blockquote>
<div class="sourceCode" id="cb10"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb10-1"><a href="#cb10-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> f(x: <span class="bu">float</span>) <span class="op">-></span> <span class="bu">float</span></span></code></pre></div>
</div>
</section>
<section id="benefit-reasoning-1" class="slide level2">
<h2>Benefit: Reasoning</h2>
<div class="sourceCode" id="cb11"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb11-1"><a href="#cb11-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> minimum(values) <span class="co"># pure</span></span>
<span id="cb11-2"><a href="#cb11-2" aria-hidden="true" tabindex="-1"></a> <span class="co"># values.sort() </span></span>
<span id="cb11-3"><a href="#cb11-3" aria-hidden="true" tabindex="-1"></a> other <span class="op">=</span> <span class="bu">sorted</span>(values) <span class="co"># no mutation</span></span>
<span id="cb11-4"><a href="#cb11-4" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> other[<span class="dv">0</span>]</span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb12"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb12-1"><a href="#cb12-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main()</span>
<span id="cb12-2"><a href="#cb12-2" aria-hidden="true" tabindex="-1"></a> prices <span class="op">=</span> [<span class="dv">5</span>,<span class="dv">2</span>,<span class="dv">7</span>] </span>
<span id="cb12-3"><a href="#cb12-3" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5 </span></span>
<span id="cb12-4"><a href="#cb12-4" aria-hidden="true" tabindex="-1"></a> minPrice <span class="op">=</span> minimum(prices) <span class="co"># pure</span></span>
<span id="cb12-5"><a href="#cb12-5" aria-hidden="true" tabindex="-1"></a> <span class="co"># assert prices[0] == 5! </span></span></code></pre></div>
</div>
</section>
<section id="benefit-testing" class="slide level2">
<h2>Benefit: Testing</h2>
<div class="sourceCode" id="cb13"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb13-1"><a href="#cb13-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> test() </span>
<span id="cb13-2"><a href="#cb13-2" aria-hidden="true" tabindex="-1"></a> values <span class="op">=</span> [<span class="dv">5</span>,<span class="dv">2</span>,<span class="dv">7</span>] <span class="co"># data </span></span>
<span id="cb13-3"><a href="#cb13-3" aria-hidden="true" tabindex="-1"></a> expected <span class="op">=</span> <span class="dv">2</span></span>
<span id="cb13-4"><a href="#cb13-4" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-5"><a href="#cb13-5" aria-hidden="true" tabindex="-1"></a> out <span class="op">=</span> minimum(values) <span class="co"># pure</span></span>
<span id="cb13-6"><a href="#cb13-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb13-7"><a href="#cb13-7" aria-hidden="true" tabindex="-1"></a> <span class="cf">assert</span> out <span class="op">==</span> expected </span></code></pre></div>
<div class="fragment">
<blockquote>
<p><em>cost(data) < cost(classes)</em></p>
</blockquote>
</div>
</section>
<section id="benefit-refactoring" class="slide level2">
<h2>Benefit: Refactoring</h2>
<p>Referential transparency:</p>
<div class="sourceCode" id="cb14"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb14-1"><a href="#cb14-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main():</span>
<span id="cb14-2"><a href="#cb14-2" aria-hidden="true" tabindex="-1"></a> y <span class="op">=</span> compute(<span class="dv">5</span>,<span class="dv">2</span>) <span class="op">+</span> <span class="dv">7</span></span>
<span id="cb14-3"><a href="#cb14-3" aria-hidden="true" tabindex="-1"></a> z <span class="op">=</span> compute(<span class="dv">5</span>,<span class="dv">2</span>) <span class="op">+</span> <span class="dv">1</span></span></code></pre></div>
<div class="fragment">
<p>=</p>
<div class="sourceCode" id="cb15"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb15-1"><a href="#cb15-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main():</span>
<span id="cb15-2"><a href="#cb15-2" aria-hidden="true" tabindex="-1"></a> x <span class="op">=</span> compute(<span class="dv">5</span>,<span class="dv">2</span>) <span class="co"># Factored out</span></span>
<span id="cb15-3"><a href="#cb15-3" aria-hidden="true" tabindex="-1"></a> y <span class="op">=</span> x <span class="op">+</span> <span class="dv">7</span></span>
<span id="cb15-4"><a href="#cb15-4" aria-hidden="true" tabindex="-1"></a> z <span class="op">=</span> x <span class="op">+</span> <span class="dv">1</span></span></code></pre></div>
</div>
<div class="fragment">
<p>Fearless refactoring, also by compiler</p>
</div>
</section>
<section id="impure-functions" class="slide level2">
<h2>Impure Functions</h2>
<p>No referential transparency:</p>
<div class="sourceCode" id="cb16"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb16-1"><a href="#cb16-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main(): <span class="co"># 2 side-effects</span></span>
<span id="cb16-2"><a href="#cb16-2" aria-hidden="true" tabindex="-1"></a> y <span class="op">=</span> randomNumber() <span class="op">+</span> <span class="dv">7</span> </span>
<span id="cb16-3"><a href="#cb16-3" aria-hidden="true" tabindex="-1"></a> z <span class="op">=</span> randomNumber() <span class="op">+</span> <span class="dv">1</span> </span></code></pre></div>
<div class="fragment">
<p>!=</p>
<div class="sourceCode" id="cb17"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb17-1"><a href="#cb17-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main(): <span class="co"># 1 side-effect</span></span>
<span id="cb17-2"><a href="#cb17-2" aria-hidden="true" tabindex="-1"></a> x <span class="op">=</span> randomNumber() <span class="co"># Factored out</span></span>
<span id="cb17-3"><a href="#cb17-3" aria-hidden="true" tabindex="-1"></a> y <span class="op">=</span> x <span class="op">+</span> <span class="dv">7</span></span>
<span id="cb17-4"><a href="#cb17-4" aria-hidden="true" tabindex="-1"></a> z <span class="op">=</span> x <span class="op">+</span> <span class="dv">1</span></span></code></pre></div>
</div>
<div class="fragment">
<p>Careful refactoring, often manual</p>
</div>
</section>
<section id="benefit-abstraction" class="slide level2">
<h2>Benefit: Abstraction</h2>
<div class="sourceCode" id="cb18"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb18-1"><a href="#cb18-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> f(_: Char) <span class="op">-></span> Int</span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb19"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb19-1"><a href="#cb19-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> toAscii(c: Char) <span class="op">-></span> Int</span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb20"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb20-1"><a href="#cb20-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> f(_: [Any]) <span class="op">-></span> Int</span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb21"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb21-1"><a href="#cb21-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> length(<span class="bu">list</span>: [Any]) <span class="op">-></span> Int</span></code></pre></div>
<p>Types often enough for understanding.</p>
</div>
</section>
<section id="impure-functions-1" class="slide level2">
<h2>Impure Functions</h2>
<div class="sourceCode" id="cb22"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb22-1"><a href="#cb22-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> f() <span class="op">-></span> <span class="va">None</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb23"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb23-1"><a href="#cb23-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> performTask() <span class="op">-></span> <span class="va">None</span></span>
<span id="cb23-2"><a href="#cb23-2" aria-hidden="true" tabindex="-1"></a> inputs <span class="op">=</span> loadInputs()</span>
<span id="cb23-3"><a href="#cb23-3" aria-hidden="true" tabindex="-1"></a> computeResult(inputs)</span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb24"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb24-1"><a href="#cb24-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> launchMissiles() <span class="op">-></span> <span class="va">None</span></span>
<span id="cb24-2"><a href="#cb24-2" aria-hidden="true" tabindex="-1"></a> coord <span class="op">=</span> loadCoordinates()</span>
<span id="cb24-3"><a href="#cb24-3" aria-hidden="true" tabindex="-1"></a> ...</span></code></pre></div>
<p>Need to look at body to be sure.</p>
</div>
</section>
<section id="classical-oo" class="slide level2">
<h2>Classical OO</h2>
<div class="sourceCode" id="cb25"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb25-1"><a href="#cb25-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass</span>
<span id="cb25-2"><a href="#cb25-2" aria-hidden="true" tabindex="-1"></a> state: LotsOfState <span class="co"># private</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb26"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb26-1"><a href="#cb26-1" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> do() <span class="op">-></span> <span class="va">None</span> <span class="co"># public</span></span>
<span id="cb26-2"><a href="#cb26-2" aria-hidden="true" tabindex="-1"></a> state.do_a() </span>
<span id="cb26-3"><a href="#cb26-3" aria-hidden="true" tabindex="-1"></a> state.do_b() </span>
<span id="cb26-4"><a href="#cb26-4" aria-hidden="true" tabindex="-1"></a> this._do() </span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb27"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb27-1"><a href="#cb27-1" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> _do() <span class="co"># private</span></span>
<span id="cb27-2"><a href="#cb27-2" aria-hidden="true" tabindex="-1"></a> state.do_c()</span>
<span id="cb27-3"><a href="#cb27-3" aria-hidden="true" tabindex="-1"></a> ...</span></code></pre></div>
</div>
</section>
<section id="classical-oo-1" class="slide level2">
<h2>Classical OO</h2>
<div class="columns">
<div class="column" style="width:50%;">
<div class="sourceCode" id="cb28"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb28-1"><a href="#cb28-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass</span>
<span id="cb28-2"><a href="#cb28-2" aria-hidden="true" tabindex="-1"></a> state: LotsOfState</span>
<span id="cb28-3"><a href="#cb28-3" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb28-4"><a href="#cb28-4" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> do() <span class="op">-></span> <span class="va">None</span></span>
<span id="cb28-5"><a href="#cb28-5" aria-hidden="true" tabindex="-1"></a> state.do_a()</span>
<span id="cb28-6"><a href="#cb28-6" aria-hidden="true" tabindex="-1"></a> state.do_b()</span>
<span id="cb28-7"><a href="#cb28-7" aria-hidden="true" tabindex="-1"></a> this._do()</span>
<span id="cb28-8"><a href="#cb28-8" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb28-9"><a href="#cb28-9" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> _do()</span>
<span id="cb28-10"><a href="#cb28-10" aria-hidden="true" tabindex="-1"></a> state.do_c()</span>
<span id="cb28-11"><a href="#cb28-11" aria-hidden="true" tabindex="-1"></a> ...</span></code></pre></div>
</div><div class="column" style="width:50%;">
<p><img
data-src="plantuml-images/9386d3751eaf14158eeb0f3212e7d36f6d734438.png" /></p>
</div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb29"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb29-1"><a href="#cb29-1" aria-hidden="true" tabindex="-1"></a>...</span>
<span id="cb29-2"><a href="#cb29-2" aria-hidden="true" tabindex="-1"></a>myClass.do()</span>
<span id="cb29-3"><a href="#cb29-3" aria-hidden="true" tabindex="-1"></a>...</span></code></pre></div>
</div>
</section>
<section id="fp-ish-oo" class="slide level2">
<h2>FP-ish OO</h2>
<div class="sourceCode" id="cb30"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb30-1"><a href="#cb30-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass</span>
<span id="cb30-2"><a href="#cb30-2" aria-hidden="true" tabindex="-1"></a> constants</span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb31"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb31-1"><a href="#cb31-1" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> do(start) <span class="co"># Pure </span></span>
<span id="cb31-2"><a href="#cb31-2" aria-hidden="true" tabindex="-1"></a> x <span class="op">=</span> do_a(start) <span class="co"># No mutation</span></span>
<span id="cb31-3"><a href="#cb31-3" aria-hidden="true" tabindex="-1"></a> y <span class="op">=</span> do_b(x, constants) <span class="co"># No mutation</span></span>
<span id="cb31-4"><a href="#cb31-4" aria-hidden="true" tabindex="-1"></a> z <span class="op">=</span> this._do(y) <span class="co"># No mutation</span></span>
<span id="cb31-5"><a href="#cb31-5" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> z</span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb32"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb32-1"><a href="#cb32-1" aria-hidden="true" tabindex="-1"></a> </span>
<span id="cb32-2"><a href="#cb32-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> _do(y) <span class="co"># Pure</span></span>
<span id="cb32-3"><a href="#cb32-3" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> do_c(y, constants) <span class="co"># No mutation</span></span></code></pre></div>
</div>
</section>
<section id="global-mutation" class="slide level2">
<h2>Global Mutation</h2>
<div class="sourceCode" id="cb33"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb33-1"><a href="#cb33-1" aria-hidden="true" tabindex="-1"></a>state: LotsOfState <span class="co"># Global variable</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb34"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb34-1"><a href="#cb34-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> someOperation() </span>
<span id="cb34-2"><a href="#cb34-2" aria-hidden="true" tabindex="-1"></a> state.do_a() <span class="co"># Global mutation</span></span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb35"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb35-1"><a href="#cb35-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main() </span>
<span id="cb35-2"><a href="#cb35-2" aria-hidden="true" tabindex="-1"></a> ...</span>
<span id="cb35-3"><a href="#cb35-3" aria-hidden="true" tabindex="-1"></a> someOperation() </span>
<span id="cb35-4"><a href="#cb35-4" aria-hidden="true" tabindex="-1"></a> ...</span></code></pre></div>
</div>
</section>
<section id="class-mutation" class="slide level2">
<h2>Class Mutation</h2>
<div class="sourceCode" id="cb36"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb36-1"><a href="#cb36-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass</span>
<span id="cb36-2"><a href="#cb36-2" aria-hidden="true" tabindex="-1"></a> state: LotsOfState <span class="co"># Class variable</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb37"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb37-1"><a href="#cb37-1" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> someOperation() </span>
<span id="cb37-2"><a href="#cb37-2" aria-hidden="true" tabindex="-1"></a> state.do_a() <span class="co"># Class mutation</span></span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb38"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb38-1"><a href="#cb38-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> main() </span>
<span id="cb38-2"><a href="#cb38-2" aria-hidden="true" tabindex="-1"></a> ...</span>
<span id="cb38-3"><a href="#cb38-3" aria-hidden="true" tabindex="-1"></a> myClass.someOperation() </span>
<span id="cb38-4"><a href="#cb38-4" aria-hidden="true" tabindex="-1"></a> ...</span></code></pre></div>
</div>
</section>
<section id="output-arguments" class="slide level2">
<h2>Output arguments</h2>
<p>Not ok:</p>
<div class="sourceCode" id="cb39"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb39-1"><a href="#cb39-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> do(state): </span>
<span id="cb39-2"><a href="#cb39-2" aria-hidden="true" tabindex="-1"></a> <span class="co"># ... modify argument 'state'</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb40"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb40-1"><a href="#cb40-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> do(state) <span class="co"># 'state' mutated</span></span></code></pre></div>
</div>
<div class="fragment">
<p>So why should this?</p>
<div class="sourceCode" id="cb41"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb41-1"><a href="#cb41-1" aria-hidden="true" tabindex="-1"></a>x <span class="op">=</span> state.do() <span class="co"># 'state' mutated</span></span></code></pre></div>
</div>
<div class="fragment">
<div class="sourceCode" id="cb42"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb42-1"><a href="#cb42-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> State:</span>
<span id="cb42-2"><a href="#cb42-2" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb42-3"><a href="#cb42-3" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> do(<span class="va">self</span>): <span class="co"># 'self' is 'state'</span></span>
<span id="cb42-4"><a href="#cb42-4" aria-hidden="true" tabindex="-1"></a> <span class="co"># ... modify argument self</span></span></code></pre></div>
</div>
</section>
<section id="how-to-side-effects" class="slide level2">
<h2>How to Side-Effects</h2>
<div class="sourceCode" id="cb43"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb43-1"><a href="#cb43-1" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> performTask() </span>
<span id="cb43-2"><a href="#cb43-2" aria-hidden="true" tabindex="-1"></a> inputs <span class="op">=</span> fetchInputs() <span class="co"># IO</span></span>
<span id="cb43-3"><a href="#cb43-3" aria-hidden="true" tabindex="-1"></a> result <span class="op">=</span> <span class="dv">2</span><span class="op">*</span>inputs </span>
<span id="cb43-4"><a href="#cb43-4" aria-hidden="true" tabindex="-1"></a> publish(result) <span class="co"># IO</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb44"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb44-1"><a href="#cb44-1" aria-hidden="true" tabindex="-1"></a><span class="co"># Infrastructure/Application layer # Impure</span></span>
<span id="cb44-2"><a href="#cb44-2" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> performTask() </span>
<span id="cb44-3"><a href="#cb44-3" aria-hidden="true" tabindex="-1"></a> inputs <span class="op">=</span> fetchInputs() </span>
<span id="cb44-4"><a href="#cb44-4" aria-hidden="true" tabindex="-1"></a> result <span class="op">=</span> domainLogic(inputs) </span>
<span id="cb44-5"><a href="#cb44-5" aria-hidden="true" tabindex="-1"></a> publish(result) </span>
<span id="cb44-6"><a href="#cb44-6" aria-hidden="true" tabindex="-1"></a></span>
<span id="cb44-7"><a href="#cb44-7" aria-hidden="true" tabindex="-1"></a><span class="co"># Domain layer</span></span>
<span id="cb44-8"><a href="#cb44-8" aria-hidden="true" tabindex="-1"></a><span class="kw">def</span> domainLogic(inputs) <span class="co"># Pure</span></span>
<span id="cb44-9"><a href="#cb44-9" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> <span class="dv">2</span><span class="op">*</span>inputs</span>
<span id="cb44-10"><a href="#cb44-10" aria-hidden="true" tabindex="-1"></a> </span></code></pre></div>
<blockquote>
<p><em>Separate IO and logic</em></p>
</blockquote>
</div>
</section>
<section id="further-topics" class="slide level2">
<h2>Further Topics</h2>
<div class="columns">
<div class="column" style="width:50%;">
<p>Try</p>
<ul>
<li>Scala</li>
<li>Rust</li>
<li>Haskell</li>
</ul>
</div><div class="column" style="width:50%;">
<p><small> Category Theory </small></p>
<p><img data-src="img/category_theory.svg" style="width:40.0%" /></p>
<ul>
<li>Algebraic Data Types</li>
<li>Functor (map)</li>
<li>Monad (flatMap)</li>
<li>Lens …</li>
</ul>
</div>
</div>
<aside class="notes">
<p>Image is public domain</p>
</aside>
</section>
<section id="questions" class="slide level2">
<h2>Questions?</h2>
<p>Thanks</p>
</section>
<section id="type-checker-support" class="slide level2">
<h2>Type Checker Support</h2>
<blockquote>
<p><em>Make illegal state (more) unrepresentable</em></p>
</blockquote>
</section>
<section id="immutable-built-in-classes" class="slide level2">
<h2>Immutable Built-in Classes</h2>
<p>Immutable interface:</p>
<div class="sourceCode" id="cb45"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb45-1"><a href="#cb45-1" aria-hidden="true" tabindex="-1"></a>mySet <span class="op">=</span> <span class="bu">frozenset</span>([<span class="dv">1</span>, <span class="dv">2</span>, <span class="dv">3</span>]) <span class="co"># Python</span></span>
<span id="cb45-2"><a href="#cb45-2" aria-hidden="true" tabindex="-1"></a>mySet.add(<span class="dv">4</span>) <span class="co"># type error</span></span></code></pre></div>
<div class="fragment">
<p>Copy on change:</p>
<div class="sourceCode" id="cb46"><pre
class="sourceCode scala"><code class="sourceCode scala"><span id="cb46-1"><a href="#cb46-1" aria-hidden="true" tabindex="-1"></a><span class="kw">val</span> myList <span class="op">=</span> immutable<span class="op">.</span><span class="ex">List</span><span class="op">(</span><span class="dv">1</span><span class="op">,</span> <span class="dv">2</span><span class="op">,</span> <span class="dv">3</span><span class="op">)</span> <span class="co">// Scala</span></span>
<span id="cb46-2"><a href="#cb46-2" aria-hidden="true" tabindex="-1"></a><span class="kw">val</span> other <span class="op">=</span> myList<span class="op">.</span><span class="fu">appended</span><span class="op">(</span><span class="dv">4</span><span class="op">)</span> <span class="co">// other list</span></span></code></pre></div>
</div>
</section>
<section id="immutable-custom-classes" class="slide level2">
<h2>Immutable Custom Classes</h2>
<p>Immutable interface around mutable data:</p>
<div class="sourceCode" id="cb47"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb47-1"><a href="#cb47-1" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass: </span>
<span id="cb47-2"><a href="#cb47-2" aria-hidden="true" tabindex="-1"></a> _value: <span class="bu">int</span> <span class="co"># hide mutables</span></span>
<span id="cb47-3"><a href="#cb47-3" aria-hidden="true" tabindex="-1"></a> </span>
<span id="cb47-4"><a href="#cb47-4" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> getValue() <span class="co"># no setters</span></span>
<span id="cb47-5"><a href="#cb47-5" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> _value</span>
<span id="cb47-6"><a href="#cb47-6" aria-hidden="true" tabindex="-1"></a> </span>
<span id="cb47-7"><a href="#cb47-7" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> calcSth() <span class="co"># _value read only</span></span>
<span id="cb47-8"><a href="#cb47-8" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> _value<span class="op">*</span><span class="dv">2</span></span>
<span id="cb47-9"><a href="#cb47-9" aria-hidden="true" tabindex="-1"></a> </span>
<span id="cb47-10"><a href="#cb47-10" aria-hidden="true" tabindex="-1"></a> <span class="kw">def</span> incremented() <span class="co"># Copy on change</span></span>
<span id="cb47-11"><a href="#cb47-11" aria-hidden="true" tabindex="-1"></a> <span class="cf">return</span> MyClass(_value<span class="op">+</span><span class="dv">1</span>)</span></code></pre></div>
</section>
<section id="immutable-custom-classes-1" class="slide level2">
<h2>Immutable Custom Classes</h2>
<p>With extra language support:</p>
<div class="sourceCode" id="cb48"><pre
class="sourceCode python"><code class="sourceCode python"><span id="cb48-1"><a href="#cb48-1" aria-hidden="true" tabindex="-1"></a><span class="at">@dataclass</span>(frozen<span class="op">=</span><span class="va">True</span>) <span class="co"># Python</span></span>
<span id="cb48-2"><a href="#cb48-2" aria-hidden="true" tabindex="-1"></a><span class="kw">class</span> MyClass:</span>
<span id="cb48-3"><a href="#cb48-3" aria-hidden="true" tabindex="-1"></a> value: <span class="bu">int</span></span>
<span id="cb48-4"><a href="#cb48-4" aria-hidden="true" tabindex="-1"></a> </span>
<span id="cb48-5"><a href="#cb48-5" aria-hidden="true" tabindex="-1"></a><span class="bu">object</span> <span class="op">=</span> MyClass(<span class="dv">1</span>)</span>
<span id="cb48-6"><a href="#cb48-6" aria-hidden="true" tabindex="-1"></a><span class="bu">object</span>.value <span class="op">=</span> <span class="dv">2</span> <span class="co"># compile error!</span></span></code></pre></div>
<div class="fragment">
<div class="sourceCode" id="cb49"><pre
class="sourceCode typescript"><code class="sourceCode typescript"><span id="cb49-1"><a href="#cb49-1" aria-hidden="true" tabindex="-1"></a><span class="kw">interface</span> MyInterface { <span class="co">// Typescript</span></span>
<span id="cb49-2"><a href="#cb49-2" aria-hidden="true" tabindex="-1"></a> <span class="kw">readonly</span> value<span class="op">:</span> int<span class="op">;</span></span>
<span id="cb49-3"><a href="#cb49-3" aria-hidden="true" tabindex="-1"></a>}</span></code></pre></div>
</div>
</section>
<section id="immutable-variables" class="slide level2">
<h2>Immutable Variables</h2>
<p>Mutable:</p>
<div class="sourceCode" id="cb50"><pre
class="sourceCode typescript"><code class="sourceCode typescript"><span id="cb50-1"><a href="#cb50-1" aria-hidden="true" tabindex="-1"></a><span class="kw">var</span> value <span class="op">=</span> <span class="dv">1</span> <span class="co">// Typescript</span></span>
<span id="cb50-2"><a href="#cb50-2" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="dv">2</span> <span class="co">// ok</span></span></code></pre></div>
<div class="fragment">
<p>Immutable:</p>
<div class="sourceCode" id="cb51"><pre
class="sourceCode typescript"><code class="sourceCode typescript"><span id="cb51-1"><a href="#cb51-1" aria-hidden="true" tabindex="-1"></a><span class="kw">const</span> value <span class="op">=</span> <span class="dv">1</span> <span class="co">// Typescript</span></span>
<span id="cb51-2"><a href="#cb51-2" aria-hidden="true" tabindex="-1"></a>value <span class="op">=</span> <span class="dv">2</span> <span class="co">// type error!</span></span></code></pre></div>
</div>
</section>
</div>
</div>
<script src="https://unpkg.com/reveal.js@^4//dist/reveal.js"></script>
<!-- reveal.js plugins -->
<script src="https://unpkg.com/reveal.js@^4//plugin/notes/notes.js"></script>
<script src="https://unpkg.com/reveal.js@^4//plugin/search/search.js"></script>
<script src="https://unpkg.com/reveal.js@^4//plugin/zoom/zoom.js"></script>
<script>
// Full list of configuration options available at:
// https://revealjs.com/config/
Reveal.initialize({
// Display controls in the bottom right corner
controls: true,
// Help the user learn the controls by providing hints, for example by
// bouncing the down arrow when they first encounter a vertical slide
controlsTutorial: true,
// Determines where controls appear, "edges" or "bottom-right"
controlsLayout: 'bottom-right',
// Visibility rule for backwards navigation arrows; "faded", "hidden"
// or "visible"
controlsBackArrows: 'faded',
// Display a presentation progress bar
progress: true,
// Display the page number of the current slide
slideNumber: true,
// 'all', 'print', or 'speaker'
showSlideNumber: 'all',
// Add the current slide number to the URL hash so that reloading the
// page/copying the URL will return you to the same slide
hash: true,
// Start with 1 for the hash rather than 0
hashOneBasedIndex: false,
// Flags if we should monitor the hash and change slides accordingly
respondToHashChanges: true,
// Push each slide change to the browser history
history: false,
// Enable keyboard shortcuts for navigation
keyboard: true,
// Enable the slide overview mode
overview: true,
// Disables the default reveal.js slide layout (scaling and centering)
// so that you can use custom CSS layout
disableLayout: false,
// Vertical centering of slides
center: true,
// Enables touch navigation on devices with touch input
touch: true,
// Loop the presentation
loop: false,
// Change the presentation direction to be RTL
rtl: false,
// see https://revealjs.com/vertical-slides/#navigation-mode
navigationMode: 'default',
// Randomizes the order of slides each time the presentation loads
shuffle: false,
// Turns fragments on and off globally
fragments: true,
// Flags whether to include the current fragment in the URL,
// so that reloading brings you to the same fragment position
fragmentInURL: true,
// Flags if the presentation is running in an embedded mode,
// i.e. contained within a limited portion of the screen
embedded: false,
// Flags if we should show a help overlay when the questionmark
// key is pressed
help: true,
// Flags if it should be possible to pause the presentation (blackout)
pause: true,
// Flags if speaker notes should be visible to all viewers
showNotes: false,
// Global override for autoplaying embedded media (null/true/false)
autoPlayMedia: null,
// Global override for preloading lazy-loaded iframes (null/true/false)
preloadIframes: null,
// Number of milliseconds between automatically proceeding to the
// next slide, disabled when set to 0, this value can be overwritten
// by using a data-autoslide attribute on your slides
autoSlide: 0,
// Stop auto-sliding after user input
autoSlideStoppable: true,
// Use this method for navigation when auto-sliding
autoSlideMethod: null,
// Specify the average time in seconds that you think you will spend
// presenting each slide. This is used to show a pacing timer in the
// speaker view
defaultTiming: null,
// Enable slide navigation via mouse wheel
mouseWheel: false,
// The display mode that will be used to show slides
display: 'block',
// Hide cursor if inactive
hideInactiveCursor: true,
// Time before the cursor is hidden (in ms)
hideCursorTime: 5000,
// Opens links in an iframe preview overlay
previewLinks: false,
// Transition style (none/fade/slide/convex/concave/zoom)
transition: 'none',
// Transition speed (default/fast/slow)
transitionSpeed: 'default',
// Transition style for full page slide backgrounds
// (none/fade/slide/convex/concave/zoom)
backgroundTransition: 'fade',
// Number of slides away from the current that are visible
viewDistance: 3,
// Number of slides away from the current that are visible on mobile
// devices. It is advisable to set this to a lower number than
// viewDistance in order to save resources.
mobileViewDistance: 2,
// reveal.js plugins
plugins: [
RevealNotes,
RevealSearch,
RevealZoom
]
});
</script>
</body>
</html>