1 1

     2 00:00:05,750 --> 00:00:10,395

     3 They come back! Before we can

     4 start with any serious work,

     5 

     6 2

     7 00:00:10,395 --> 00:00:12,255

     8 let's do some housekeeping.

     9 

    10 3

    11 00:00:12,255 --> 00:00:17,380

    12 As you know, this year is a tad special.

    13 While the broad direction is clear,

    14 

    15 4

    16 00:00:17,380 --> 00:00:19,730

    17 there are some organizational

    18 details that

    19 

    20 5

    21 00:00:19,730 --> 00:00:22,370

    22 still need to be worked

    23 out as we go along.

    24 

    25 6

    26 00:00:22,370 --> 00:00:23,930

    27 The main hub for

    28 

    29 7

    30 00:00:23,930 --> 00:00:27,215

    31 all the information is the

    32 KEATS page of this module.

    33 

    34 8

    35 00:00:27,215 --> 00:00:29,300

    36 Let me say a few words on how

    37 

    38 9

    39 00:00:29,300 --> 00:00:35,269

    40 it is organized. The module is

    41 organized into weekly topics.

    42 

    43 10

    44 00:00:35,269 --> 00:00:39,785

    45 So there are entries for weeks

    46 one up till week ten.

    47 

    48 11

    49 00:00:39,785 --> 00:00:44,390

    50 Let's also proceed in

    51 approximately weekly steps.

    52 

    53 12

    54 00:00:44,390 --> 00:00:46,790

    55 Because if you

    56 already asked me in

    57 

    58 13

    59 00:00:46,790 --> 00:00:49,130

    60 week two something

    61 about week ten,

    62 

    63 14

    64 00:00:49,130 --> 00:00:51,275

    65 then you might confuse me

    66 

    67 15

    68 00:00:51,275 --> 00:00:53,720

    69 and also your fellow students.

    70 

    71 16

    72 00:00:53,720 --> 00:00:55,970

    73 All the communication in

    74 

    75 17

    76 00:00:55,970 --> 00:00:59,945

    77 this module can be done in

    78 the course discussion area.

    79 

    80 18

    81 00:00:59,945 --> 00:01:02,300

    82 You can ask any questions.

    83 

    84 19

    85 00:01:02,300 --> 00:01:05,465

    86 For example, I haven't

    87 understood this point,

    88 

    89 20

    90 00:01:05,465 --> 00:01:07,910

    91 this video isn't clear,

    92 

    93 21

    94 00:01:07,910 --> 00:01:10,160

    95 I cannot run this code,

    96 

    97 22

    98 00:01:10,160 --> 00:01:13,910

    99 I have problems with

   100 accessing the coursework.

   101 

   102 23

   103 00:01:13,910 --> 00:01:16,295

   104 This can be all discussed here.

   105 

   106 24

   107 00:01:16,295 --> 00:01:18,590

   108 If you have any private matter,

   109 

   110 25

   111 00:01:18,590 --> 00:01:20,900

   112 like, I can't understand why

   113 

   114 26

   115 00:01:20,900 --> 00:01:23,465

   116 did I get such a good

   117 mark, for example?

   118 

   119 27

   120 00:01:23,465 --> 00:01:27,245

   121 Or there are some private

   122 reasons why you can't keep up.

   123 

   124 28

   125 00:01:27,245 --> 00:01:31,430

   126 Please feel free to use

   127 my private email address.

   128 

   129 29

   130 00:01:31,430 --> 00:01:35,630

   131 But for any other matter

   132 related to the module,

   133 

   134 30

   135 00:01:35,630 --> 00:01:38,480

   136 try to use the course

   137 discussion area.

   138 

   139 31

   140 00:01:38,480 --> 00:01:41,510

   141 And I will try to stay on top

   142 

   143 32

   144 00:01:41,510 --> 00:01:45,450

   145 of all the discussions

   146 as much as I can.

   147 

   148 33

   149 00:01:45,580 --> 00:01:48,500

   150 Each week is organized into

   151 

   152 34

   153 00:01:48,500 --> 00:01:52,550

   154 a mandatory section and

   155 an optional section.

   156 

   157 35

   158 00:01:52,550 --> 00:01:55,835

   159 The mandatory section

   160 contains videos,

   161 

   162 36

   163 00:01:55,835 --> 00:01:58,190

   164 a handout, and the slides,

   165 

   166 37

   167 00:01:58,190 --> 00:02:00,725

   168 which I used to

   169 produce the videos.

   170 

   171 38

   172 00:02:00,725 --> 00:02:04,324

   173 I recommend that your

   174 first read the handouts,

   175 

   176 39

   177 00:02:04,324 --> 00:02:07,430

   178 then watch the videos and then

   179 

   180 40

   181 00:02:07,430 --> 00:02:11,030

   182 read the handout

   183 again for each week.

   184 

   185 41

   186 00:02:11,030 --> 00:02:14,795

   187 Apologies, some of these

   188 handouts are quite lengthy.

   189 

   190 42

   191 00:02:14,795 --> 00:02:17,615

   192 I think the longest

   193 one is 20 pages.

   194 

   195 43

   196 00:02:17,615 --> 00:02:19,235

   197 On the good side,

   198 

   199 44

   200 00:02:19,235 --> 00:02:21,650

   201 these handouts are

   202 written in such a way

   203 

   204 45

   205 00:02:21,650 --> 00:02:24,935

   206 that you can read them just

   207 before you fall asleep

   208 

   209 46

   210 00:02:24,935 --> 00:02:26,720

   211 and you should still be able

   212 

   213 47

   214 00:02:26,720 --> 00:02:28,835

   215 to understand what is going on.

   216 

   217 48

   218 00:02:28,835 --> 00:02:32,105

   219 Also, they contain lots

   220 of pictures and code.

   221 

   222 49

   223 00:02:32,105 --> 00:02:35,330

   224 So 20 pages is

   225 a bit misleading.

   226 

   227 50

   228 00:02:35,330 --> 00:02:38,870

   229 You can see the second week

   230 is organized similarly.

   231 

   232 51

   233 00:02:38,870 --> 00:02:41,030

   234 You will have some videos.

   235 

   236 52

   237 00:02:41,030 --> 00:02:42,260

   238 You will have a handout,

   239 

   240 53

   241 00:02:42,260 --> 00:02:43,624

   242 you have the slides,

   243 

   244 54

   245 00:02:43,624 --> 00:02:45,770

   246 and some optional resources.

   247 

   248 55

   249 00:02:45,770 --> 00:02:51,410

   250 I have also put up a general

   251 section, with general

   252 

   253 56

   254 00:02:51,410 --> 00:02:57,965

   255 material, where I put

   256 a PDF about my notation.

   257 

   258 57

   259 00:02:57,965 --> 00:03:01,385

   260 This might be very

   261 useful because

   262 

   263 58

   264 00:03:01,385 --> 00:03:04,610

   265 remember this topic

   266 is already many,

   267 

   268 59

   269 00:03:04,610 --> 00:03:07,445

   270 many decades old,

   271 at least 50 years,

   272 

   273 60

   274 00:03:07,445 --> 00:03:09,185

   275 and over the time,

   276 

   277 61

   278 00:03:09,185 --> 00:03:11,510

   279 many authors and many lecturers

   280 

   281 62

   282 00:03:11,510 --> 00:03:13,745

   283 have introduced

   284 their own notation.

   285 

   286 63

   287 00:03:13,745 --> 00:03:16,565

   288 So if you read anything

   289 on the web or in books,

   290 

   291 64

   292 00:03:16,565 --> 00:03:19,640

   293 you might be confused about that

   294 

   295 65

   296 00:03:19,640 --> 00:03:24,035

   297 they call something, which

   298 I call X, they call Y.

   299 

   300 66

   301 00:03:24,035 --> 00:03:26,150

   302 So in this PDF,

   303 

   304 67

   305 00:03:26,150 --> 00:03:30,320

   306 I have collected all the

   307 information on what kind of

   308 

   309 68

   310 00:03:30,320 --> 00:03:34,940

   311 notation I am using and where

   312 I introduce some shortcuts.

   313 

   314 69

   315 00:03:34,940 --> 00:03:38,240

   316 The problem is, you always

   317 want to be precise,

   318 

   319 70

   320 00:03:38,240 --> 00:03:40,070

   321 but we also lazy.

   322 

   323 71

   324 00:03:40,070 --> 00:03:43,745

   325 We don't want to write

   326 everything into the last detail.

   327 

   328 72

   329 00:03:43,745 --> 00:03:47,375

   330 So here I say something

   331 about my notation.

   332 

   333 73

   334 00:03:47,375 --> 00:03:50,180

   335 I have also put up

   336 a document about

   337 

   338 74

   339 00:03:50,180 --> 00:03:53,510

   340 the Scala I'm going to

   341 use in this module.

   342 

   343 75

   344 00:03:53,510 --> 00:03:56,090

   345 This is important

   346 for the coursework.

   347 

   348 76

   349 00:03:56,090 --> 00:03:58,175

   350 In the coursework which

   351 will come in a moment,

   352 

   353 77

   354 00:03:58,175 --> 00:04:00,440

   355 you can use any

   356 programming language you like

   357 

   358 78

   359 00:04:00,440 --> 00:04:03,665

   360 to solve the questions and

   361 implement your code.

   362 

   363 79

   364 00:04:03,665 --> 00:04:05,615

   365 But, I'm sorry,

   366 

   367 80

   368 00:04:05,615 --> 00:04:09,830

   369 all the code I'm going to

   370 show you will be in Scala.

   371 

   372 81

   373 00:04:09,830 --> 00:04:12,155

   374 And the main difference is that

   375 

   376 82

   377 00:04:12,155 --> 00:04:15,095

   378 between PEP course from last year

   379 

   380 83

   381 00:04:15,095 --> 00:04:17,675

   382 is that I'm going to

   383 use the Ammonite

   384 

   385 84

   386 00:04:17,675 --> 00:04:21,170

   387 REPL instead of

   388 the Scala REPL.

   389 

   390 85

   391 00:04:21,170 --> 00:04:23,615

   392 They work very similarly.

   393 

   394 86

   395 00:04:23,615 --> 00:04:26,070

   396 For example,

   397 

   398 87

   399 00:04:28,120 --> 00:04:33,710

   400 I can now evaluate code

   401 and get a feedback of what

   402 

   403 88

   404 00:04:33,710 --> 00:04:37,100

   405 it calculates, just like the original one.

   406 

   407 89

   408 00:04:37,100 --> 00:04:40,220

   409 The difference is that

   410 Ammonite is

   411 

   412 90

   413 00:04:40,220 --> 00:04:42,440

   414 an extension and

   415 provides some features

   416 

   417 91

   418 00:04:42,440 --> 00:04:44,975

   419 which will be very useful for us.

   420 

   421 92

   422 00:04:44,975 --> 00:04:47,600

   423 And I recorded some

   424 of the features

   425 

   426 93

   427 00:04:47,600 --> 00:04:50,970

   428 we are going to use

   429 in this document.

   430 

   431 94

   432 00:04:52,330 --> 00:04:55,970

   433 The last point to note

   434 on the KEATS webpage

   435 

   436 95

   437 00:04:55,970 --> 00:04:59,405

   438 is that in the optional section,

   439 

   440 96

   441 00:04:59,405 --> 00:05:02,270

   442 I will always give

   443 the source code of

   444 

   445 97

   446 00:05:02,270 --> 00:05:05,845

   447 the programs I discussed

   448 in the videos and in the handouts.

   449 

   450 98

   451 00:05:05,845 --> 00:05:08,420

   452 And I really, really

   453 encourage you

   454 

   455 99

   456 00:05:08,420 --> 00:05:11,060

   457 that you play around with this code

   458 

   459 100

   460 00:05:11,060 --> 00:05:14,420

   461 to make sure you understand

   462 what was discussed.

   463 

   464 101

   465 00:05:14,420 --> 00:05:17,540

   466 At the also have sometimes

   467 some additional pointers

   468 

   469 102

   470 00:05:17,540 --> 00:05:19,490

   471 to interesting topics, which

   472 

   473 103

   474 00:05:19,490 --> 00:05:22,680

   475 you can read up in your own time.

   476 

   477 104

   478 00:05:22,690 --> 00:05:26,240

   479 Exams, I'm sorry,

   480 there will be exams.

   481 

   482 105

   483 00:05:26,240 --> 00:05:31,760

   484 There will be a final exam in

   485 January, counting for 30%.

   486 

   487 106

   488 00:05:31,760 --> 00:05:34,190

   489 There will be a

   490 midterm shortly after

   491 

   492 107

   493 00:05:34,190 --> 00:05:37,565

   494 Reading Week, accounting for 10%.

   495 

   496 108

   497 00:05:37,565 --> 00:05:40,625

   498 This will be a normal exams,

   499 

   500 109

   501 00:05:40,625 --> 00:05:44,780

   502 just that they will be online

   503 in some form or shape.

   504 

   505 110

   506 00:05:44,780 --> 00:05:49,939

   507 There will be also a weekly

   508 engagement component.

   509 

   510 111

   511 00:05:49,939 --> 00:05:52,370

   512 So 1% in each week,

   513 

   514 112

   515 00:05:52,370 --> 00:05:56,360

   516 where I make sure that

   517 you are engaged with

   518 

   519 113

   520 00:05:56,360 --> 00:06:01,625

   521 the material and you will

   522 get 1% each week for that.

   523 

   524 114

   525 00:06:01,625 --> 00:06:06,020

   526 How that is going to be

   527 working out in practice,

   528 

   529 115

   530 00:06:06,020 --> 00:06:08,000

   531 unfortunately, I do not know

   532 

   533 116

   534 00:06:08,000 --> 00:06:11,285

   535 yet what tools we use

   536 or what it means,

   537 

   538 117

   539 00:06:11,285 --> 00:06:13,685

   540 but I will let you know about it.

   541 

   542 118

   543 00:06:13,685 --> 00:06:19,295

   544 There's also an optional

   545 weekly homework.

   546 

   547 119

   548 00:06:19,295 --> 00:06:22,999

   549 The homework is

   550 uploaded on KEATS.

   551 

   552 120

   553 00:06:22,999 --> 00:06:27,230

   554 You should send your answers

   555 via email to me.

   556 

   557 121

   558 00:06:27,230 --> 00:06:31,955

   559 I will respond individually

   560 and give some feedback.

   561 

   562 122

   563 00:06:31,955 --> 00:06:33,920

   564 Normally, if everything is okay

   565 

   566 123

   567 00:06:33,920 --> 00:06:36,605

   568 with a question, I will

   569 just respond "OK"?

   570 

   571 124

   572 00:06:36,605 --> 00:06:38,630

   573 If there is

   574 something wrong,

   575 

   576 125

   577 00:06:38,630 --> 00:06:41,060

   578 I will sometimes answer with a longer

   579 

   580 126

   581 00:06:41,060 --> 00:06:44,480

   582 email. All the questions in

   583 

   584 127

   585 00:06:44,480 --> 00:06:49,415

   586 the exam and in the midterm

   587 will be from this homework.

   588 

   589 128

   590 00:06:49,415 --> 00:06:53,330

   591 So I do not give out the

   592 solutions to the homework.

   593 

   594 129

   595 00:06:53,330 --> 00:06:55,415

   596 You have to email me first

   597 

   598 130

   599 00:06:55,415 --> 00:06:57,290

   600 what do you think

   601 the solution is...

   602 

   603 131

   604 00:06:57,290 --> 00:07:01,280

   605 and I will give answers

   606 individually back.

   607 

   608 132

   609 00:07:01,280 --> 00:07:05,270

   610 And I will then ensure

   611 that all the questions in

   612 

   613 133

   614 00:07:05,270 --> 00:07:09,560

   615 the exam and the midterm coming

   616 only from this homework.

   617 

   618 134

   619 00:07:09,560 --> 00:07:11,825

   620 The simple reason for that is

   621 

   622 135

   623 00:07:11,825 --> 00:07:14,645

   624 that I hate if students ask me

   625 

   626 136

   627 00:07:14,645 --> 00:07:17,705

   628 if something is relevant

   629 for the exam or not.

   630 

   631 137

   632 00:07:17,705 --> 00:07:21,620

   633 I really like this material

   634 and whatever I tell you,

   635 

   636 138

   637 00:07:21,620 --> 00:07:23,840

   638 I feel like you

   639 should know about it.

   640 

   641 139

   642 00:07:23,840 --> 00:07:26,645

   643 So, to prevent that question,

   644 

   645 140

   646 00:07:26,645 --> 00:07:28,415

   647 if it's relevant to the exams,

   648 

   649 141

   650 00:07:28,415 --> 00:07:32,165

   651 you can just look at

   652 what's in the homework.

   653 

   654 142

   655 00:07:32,165 --> 00:07:34,370

   656 And if this question

   657 is in the homework,

   658 

   659 143

   660 00:07:34,370 --> 00:07:36,335

   661 then yes, it will be relevant.

   662 

   663 144

   664 00:07:36,335 --> 00:07:40,410

   665 And if not, it will

   666 not. Thank you.

   667 

   668 145

   669 00:07:42,280 --> 00:07:46,610

   670 Can you please make one more

   671 point about the homework?

   672 

   673 146

   674 00:07:46,610 --> 00:07:50,959

   675 Please submit your

   676 answers only as PDF.

   677 

   678 147

   679 00:07:50,959 --> 00:07:53,780

   680 That just makes it easy

   681 for me to look at.

   682 

   683 148

   684 00:07:53,780 --> 00:07:55,160

   685 Remember, I might get

   686 

   687 149

   688 00:07:55,160 --> 00:07:58,820

   689 60 or more emails about

   690 

   691 150

   692 00:07:58,820 --> 00:08:03,110

   693 that and it's just much

   694 easier for me to read PDFs.

   695 

   696 151

   697 00:08:03,110 --> 00:08:07,880

   698 Also, please in your answer

   699 copy the question.

   700 

   701 152

   702 00:08:07,880 --> 00:08:11,480

   703 I have an extremely limited memory

   704 

   705 153

   706 00:08:11,480 --> 00:08:15,290

   707 and have no idea what I actually

   708 asked in this homework until

   709 

   710 154

   711 00:08:15,290 --> 00:08:16,910

   712 I actually look it up.

   713 

   714 155

   715 00:08:16,910 --> 00:08:18,530

   716 Just to prevent that,

   717 

   718 156

   719 00:08:18,530 --> 00:08:20,255

   720 that I have to look it up myself,

   721 

   722 157

   723 00:08:20,255 --> 00:08:23,765

   724 please send in

   725 always the question

   726 

   727 158

   728 00:08:23,765 --> 00:08:26,330

   729 and then give your answer.

   730 

   731 159

   732 00:08:26,330 --> 00:08:29,915

   733 And finally, there are some

   734 

   735 160

   736 00:08:29,915 --> 00:08:32,540

   737 optional homework. They are just to

   738 

   739 161

   740 00:08:32,540 --> 00:08:34,130

   741 reminders actually that

   742 

   743 162

   744 00:08:34,130 --> 00:08:36,140

   745 you really should

   746 have a look at that.

   747 

   748 163

   749 00:08:36,140 --> 00:08:39,830

   750 But they're optional. The ones

   751 

   752 164

   753 00:08:39,830 --> 00:08:43,520

   754 that you are supposed to

   755 solve, they look like this.

   756 

   757 165

   758 00:08:43,520 --> 00:08:45,890

   759 And as I said,

   760 

   761 166

   762 00:08:45,890 --> 00:08:50,645

   763 please copy the question

   764 and then give your answer.

   765 

   766 167

   767 00:08:50,645 --> 00:08:53,780

   768 And at the end,

   769 package it into a PDF.

   770 

   771 168

   772 00:08:53,780 --> 00:08:58,505

   773 Thank you. A very

   774 important component

   775 

   776 169

   777 00:08:58,505 --> 00:09:02,240

   778 for assessment in this

   779 module is the coursework.

   780 

   781 170

   782 00:09:02,240 --> 00:09:04,160

   783 There will be five of them.

   784 

   785 171

   786 00:09:04,160 --> 00:09:06,590

   787 We will first implement a matcher.

   788 

   789 172

   790 00:09:06,590 --> 00:09:09,770

   791 Then a lexer building

   792 on top of the matcher.

   793 

   794 173

   795 00:09:09,770 --> 00:09:13,655

   796 Then build a parser

   797 and an interpreter.

   798 

   799 174

   800 00:09:13,655 --> 00:09:16,730

   801 And then a

   802 compiler for the JVM

   803 

   804 175

   805 00:09:16,730 --> 00:09:20,420

   806 and a compiler

   807 targetting the LLVM.

   808 

   809 176

   810 00:09:20,420 --> 00:09:24,155

   811 So you can see this

   812 accounts for 45%.

   813 

   814 177

   815 00:09:24,155 --> 00:09:27,200

   816 You will submit your

   817 code and you also have

   818 

   819 178

   820 00:09:27,200 --> 00:09:30,260

   821 to give some explanation

   822 about your code.

   823 

   824 179

   825 00:09:30,260 --> 00:09:31,520

   826 This will be always

   827 

   828 180

   829 00:09:31,520 --> 00:09:34,655

   830 explained in the

   831 coursework description.

   832 

   833 181

   834 00:09:34,655 --> 00:09:36,785

   835 For the coursework, you can use

   836 

   837 182

   838 00:09:36,785 --> 00:09:38,945

   839 any programming

   840 language you like.

   841 

   842 183

   843 00:09:38,945 --> 00:09:42,860

   844 In the past, people have

   845 used Haskell and Rust.

   846 

   847 184

   848 00:09:42,860 --> 00:09:45,905

   849 Obviously many go for Scala.

   850 

   851 185

   852 00:09:45,905 --> 00:09:49,730

   853 You can use any code

   854 I showed you in

   855 

   856 186

   857 00:09:49,730 --> 00:09:54,230

   858 the videos or in handouts

   859 or uploaded on KEATS.

   860 

   861 187

   862 00:09:54,230 --> 00:09:56,390

   863 But nothing else.

   864 

   865 188

   866 00:09:56,390 --> 00:09:59,450

   867 Remember, unlike

   868 in the PEP course,

   869 

   870 189

   871 00:09:59,450 --> 00:10:02,030

   872 here, in the Compiler course,

   873 

   874 190

   875 00:10:02,030 --> 00:10:04,130

   876 I actually will look with

   877 

   878 191

   879 00:10:04,130 --> 00:10:07,910

   880 my own eyes at the submissions

   881 and make judgments.

   882 

   883 192

   884 00:10:07,910 --> 00:10:13,775

   885 And I'll see if people have

   886 copied from each other.

   887 

   888 193

   889 00:10:13,775 --> 00:10:15,545

   890 Please don't do that!

   891 

   892 194

   893 00:10:15,545 --> 00:10:20,160

   894 That's very annoying

   895 for everybody involved.

   896 

   897 195

   898 00:10:20,440 --> 00:10:23,570

   899 To conclude this

   900 housekeeping video,

   901 

   902 196

   903 00:10:23,570 --> 00:10:25,580

   904 let me tell you a

   905 bit more about how

   906 

   907 197

   908 00:10:25,580 --> 00:10:28,025

   909 this module is organized.

   910 

   911 198

   912 00:10:28,025 --> 00:10:32,600

   913 The first five weeks we will

   914 spend on lexing and parsing.

   915 

   916 199

   917 00:10:32,600 --> 00:10:37,370

   918 This is essentially the

   919 frontend to our compiler.

   920 

   921 200

   922 00:10:37,370 --> 00:10:39,500

   923 The first part will

   924 be about lexing.

   925 

   926 201

   927 00:10:39,500 --> 00:10:42,995

   928 Actually, we will emphasize quite a

   929 bit on the lexing part,

   930 

   931 202

   932 00:10:42,995 --> 00:10:45,005

   933 because that's about my research.

   934 

   935 203

   936 00:10:45,005 --> 00:10:47,855

   937 And sorry, I can talk

   938 about this for hours.

   939 

   940 204

   941 00:10:47,855 --> 00:10:49,400

   942 But I also like to show you that

   943 

   944 205

   945 00:10:49,400 --> 00:10:50,750

   946 there's actually something really

   947 

   948 206

   949 00:10:50,750 --> 00:10:52,340

   950 interesting going on and

   951 I want to

   952 

   953 207

   954 00:10:52,340 --> 00:10:54,529

   955 show you a number of techniques.

   956 

   957 208

   958 00:10:54,529 --> 00:10:57,435

   959 Then obviously we have

   960 to do parsing because

   961 

   962 209

   963 00:10:57,435 --> 00:11:01,669

   964 lexing essentially only

   965 finds the words in our programs.

   966 

   967 210

   968 00:11:01,669 --> 00:11:03,860

   969 We then have to put

   970 them into sentences to

   971 

   972 211

   973 00:11:03,860 --> 00:11:07,350

   974 understand what our

   975 programs actually do.

   976 

   977 212

   978 00:11:09,820 --> 00:11:12,200

   979 The next five weeks,

   980 

   981 213

   982 00:11:12,200 --> 00:11:15,330

   983 actually that overlaps

   984 with the parsing part,

   985 

   986 214

   987 00:11:15,330 --> 00:11:18,850

   988 we will first start with

   989 writing an interpreter.

   990 

   991 215

   992 00:11:18,850 --> 00:11:20,470

   993 This is essentially to get

   994 

   995 216

   996 00:11:20,470 --> 00:11:22,285

   997 the baseline for our compiler.

   998 

   999 217

  1000 00:11:22,285 --> 00:11:24,325

  1001 Also, you will see compilers are

  1002 

  1003 218

  1004 00:11:24,325 --> 00:11:27,370

  1005 sometimes fiendishly

  1006 difficult to get correct.

  1007 

  1008 219

  1009 00:11:27,370 --> 00:11:30,880

  1010 And to actually know what

  1011 the results should be, 

  1012 

  1013 220

  1014 00:11:30,880 --> 00:11:32,320

  1015 by having it calculated with

  1016 

  1017 221

  1018 00:11:32,320 --> 00:11:35,515

  1019 an interpreter, is

  1020 really important.

  1021 

  1022 222

  1023 00:11:35,515 --> 00:11:40,030

  1024 And then we really

  1025 spent time on a compiler.

  1026 

  1027 223

  1028 00:11:40,030 --> 00:11:45,310

  1029 We will first write JVM code

  1030 for a little While language.

  1031 

  1032 224

  1033 00:11:45,310 --> 00:11:46,780

  1034 That is an extremely,

  1035 

  1036 225

  1037 00:11:46,780 --> 00:11:50,335

  1038 extremely simple C-like

  1039 language, if you want.

  1040 

  1041 226

  1042 00:11:50,335 --> 00:11:53,770

  1043 And also JVM Code for

  1044 a functional language.

  1045 

  1046 227

  1047 00:11:53,770 --> 00:11:55,615

  1048 Again, something very small.

  1049 

  1050 228

  1051 00:11:55,615 --> 00:11:57,815

  1052 And then for that

  1053 functional language

  1054 

  1055 229

  1056 00:11:57,815 --> 00:12:03,080

  1057 also generate LLVM-IR code

  1058 that can be

  1059 

  1060 230

  1061 00:12:03,080 --> 00:12:09,270

  1062 then used to generate directly

  1063 CPU code for X86 or ARM.

  1064 

  1065 231

  1066 00:12:09,460 --> 00:12:12,095

  1067 Just to whet your appetite,

  1068 

  1069 232

  1070 00:12:12,095 --> 00:12:14,780

  1071 here's the first compiler for

  1072 

  1073 233

  1074 00:12:14,780 --> 00:12:20,240

  1075 the While-language calculating

  1076 the Mandelbrot program.

  1077 

  1078 234

  1079 00:12:20,240 --> 00:12:22,160

  1080 It generates code for

  1081 

  1082 235

  1083 00:12:22,160 --> 00:12:25,460

  1084 the JVM, for the Java

  1085 virtual machine.

  1086 

  1087 236

  1088 00:12:25,460 --> 00:12:27,350

  1089 So what it first does, like in

  1090 

  1091 237

  1092 00:12:27,350 --> 00:12:29,855

  1093 the example I showed you earlier,

  1094 

  1095 238

  1096 00:12:29,855 --> 00:12:33,215

  1097 it takes the Mandelbrot

  1098 program from the BF language,

  1099 

  1100 239

  1101 00:12:33,215 --> 00:12:35,480

  1102 generates a While program

  1103 

  1104 240

  1105 00:12:35,480 --> 00:12:38,520

  1106 in our language we are

  1107 going to implement...

  1108 

  1109 241

  1110 00:12:38,530 --> 00:12:40,940

  1111 this has produced a program which is

  1112 

  1113 242

  1114 00:12:40,940 --> 00:12:44,795

  1115 approximately 70k of source code.

  1116 

  1117 243

  1118 00:12:44,795 --> 00:12:47,585

  1119 Then our compiler produced

  1120 

  1121 244

  1122 00:12:47,585 --> 00:12:53,015

  1123 a Java Virtual Machine

  1124 byte code file.

  1125 

  1126 245

  1127 00:12:53,015 --> 00:12:54,890

  1128 This is the readable version of

  1129 

  1130 246

  1131 00:12:54,890 --> 00:12:57,500

  1132 the Java Virtual Machine bytecode.

  1133 

  1134 247

  1135 00:12:57,500 --> 00:12:59,480