1
00:00:00,299 --> 00:00:04,140
hello everybody welcome back to the next
jam session

2
00:00:04,140 --> 00:00:07,279
for fp1 the long course

3
00:00:07,279 --> 00:00:11,230
an and what we're going to do and this
time

4
00:00:11,230 --> 00:00:14,799
is look at functional programming and
dart

5
00:00:14,799 --> 00:00:18,000
darts is in your language from Google

6
00:00:18,000 --> 00:00:21,810
an 8 at programming web applications

7
00:00:21,810 --> 00:00:25,350
and and art as great support

8
00:00:25,350 --> 00:00:29,820
for functional programming if you come
from Java or from C sharp

9
00:00:29,820 --> 00:00:33,440
you will feel immediately familiar with
the dark syntax

10
00:00:33,440 --> 00:00:36,940
and if you'd followed has collectors

11
00:00:36,940 --> 00:00:40,110
you will be able to take all the things
you learned there

12
00:00:40,110 --> 00:00:44,280
and immediately apply them to doctor
let's open up the other

13
00:00:44,280 --> 00:00:47,700
and and play and around with dart

14
00:00:47,700 --> 00:00:51,270
little bit and see and how we can apply

15
00:00:51,270 --> 00:00:55,969
what we learnt one and interesting
aspect of dart

16
00:00:55,969 --> 00:01:00,020
is that dart has optional typing so it's
not

17
00:01:00,020 --> 00:01:03,170
an statically typed but you can

18
00:01:03,170 --> 00:01:06,710
good and types and she wanted an

19
00:01:06,710 --> 00:01:10,619
it's not like JavaScript where you know
it's completely dynamically typed

20
00:01:10,619 --> 00:01:12,030
there's no way to put

21
00:01:12,030 --> 00:01:16,729
type annotations and I must say and
practice

22
00:01:16,729 --> 00:01:23,729
this works out very very well the nice
thing about high school

23
00:01:25,110 --> 00:01:29,770
is that the Haskell type inference is
very powerful

24
00:01:29,770 --> 00:01:35,140
and to you had never have to ride any
docs yourselves in typically

25
00:01:35,140 --> 00:01:38,310
the compiler will be able to infer
things for you

26
00:01:38,310 --> 00:01:41,810
but the price you pay for that

27
00:01:41,810 --> 00:01:45,610
is that you have to know there's a
couple of things in in Haskell wary eye

28
00:01:45,610 --> 00:01:50,070
type names have to start with Arbor
gates in Baltimore you have typed losses

29
00:01:50,070 --> 00:01:54,350
user name in there it's gonna be a use
for ever you cannot

30
00:01:54,350 --> 00:01:58,840
have that in a different class and and
art

31
00:01:58,840 --> 00:02:02,820
it's a little bit more an yeah

32
00:02:02,820 --> 00:02:06,210
hecker ish and and I i like that so that
sack

33
00:02:06,210 --> 00:02:09,429
open up and ellijay I'm using the

34
00:02:09,429 --> 00:02:13,230
dart and ellijay plugin and you can
download

35
00:02:13,230 --> 00:02:17,560
a that plug n from the intelligent
website you download

36
00:02:17,560 --> 00:02:20,900
the dark SDK from the dark website

37
00:02:20,900 --> 00:02:24,280
and of you go up

38
00:02:24,280 --> 00:02:27,880
like most languages start also

39
00:02:27,880 --> 00:02:32,430
uses a main mad at you receive the men
matted we don't have to specify

40
00:02:32,430 --> 00:02:36,090
weather takes any arguments and then
here

41
00:02:36,090 --> 00:02:40,880
we just print lol the next line here

42
00:02:40,880 --> 00:02:45,010
shows a love the expression and our two
nd

43
00:02:45,010 --> 00:02:49,090
defining a at variable af

44
00:02:49,090 --> 00:02:53,150
an and its value is a long expression
love the axe

45
00:02:53,150 --> 00:02:56,940
explosion wrong here you see that this
thing has

46
00:02:56,940 --> 00:03:00,239
a I am function type 10 let's

47
00:03:00,239 --> 00:03:04,170
just tried to say after blass at three
that see

48
00:03:04,170 --> 00:03:07,470
an welded and us and

49
00:03:07,470 --> 00:03:11,560
now you see I'm and you cannot see that

50
00:03:11,560 --> 00:03:15,890
and are it's it's it's quite small I
don't know how to blow up

51
00:03:15,890 --> 00:03:19,350
the Taipans but I will read it for you

52
00:03:19,350 --> 00:03:22,730
and it says there is no such

53
00:03:22,730 --> 00:03:26,630
operator loss in function so even though

54
00:03:26,630 --> 00:03:29,940
I didn't good day to die

55
00:03:29,940 --> 00:03:33,310
on the half the compiler has inferred

56
00:03:33,310 --> 00:03:36,850
that after has type function and that
there's no

57
00:03:36,850 --> 00:03:40,239
addition operator for function but yeah

58
00:03:40,239 --> 00:03:43,680
it will just let me continue

59
00:03:43,680 --> 00:03:47,720
and yeah if I want to do this it will
let me do

60
00:03:47,720 --> 00:03:51,110
because the typing is optional okay but
ya

61
00:03:51,110 --> 00:03:55,489
I'm not going to do this year but that's
a beautiful thing showed it

62
00:03:55,489 --> 00:04:00,160
the type infrastructure dives but
nothing is forced to you that the

63
00:04:00,160 --> 00:04:03,030
compiler will never slap you on your
wrist and say

64
00:04:03,030 --> 00:04:09,410
Eric you cannot execute this program
Sheree ever function and we can call it

65
00:04:09,410 --> 00:04:12,570
three now let's define an

66
00:04:12,570 --> 00:04:16,109
another local function that's another

67
00:04:16,109 --> 00:04:19,269
nice thing of dart and we show that in

68
00:04:19,269 --> 00:04:22,530
and other languages like skyline got
line as well is that

69
00:04:22,530 --> 00:04:26,710
inside a function you can define a local
functions are here

70
00:04:26,710 --> 00:04:30,289
inside main I'm defining local function

71
00:04:30,289 --> 00:04:37,240
G and this G can refer to dish out or
variable at and show it closes over at

72
00:04:37,240 --> 00:04:39,319
and what she does is it calls

73
00:04:39,319 --> 00:04:43,340
have a fax and then multiply it by two
and then here I print

74
00:04:43,340 --> 00:04:46,759
gr4 now let's look at

75
00:04:46,759 --> 00:04:50,210
a.m. a real higher I read a function

76
00:04:50,210 --> 00:04:53,210
a.m. our good friend twice

77
00:04:53,210 --> 00:04:57,319
so twice an takes two parameters

78
00:04:57,319 --> 00:05:00,340
af an axe and I call af

79
00:05:00,340 --> 00:05:04,279
of affects so easy it is looks just

80
00:05:04,279 --> 00:05:07,490
like an the along the expression

81
00:05:07,490 --> 00:05:10,960
and has call am and I

82
00:05:10,960 --> 00:05:14,659
if I wanted you know we could and also

83
00:05:14,659 --> 00:05:18,599
define it like this really good defined
far too wise

84
00:05:18,599 --> 00:05:22,099
equals am and now

85
00:05:22,099 --> 00:05:25,719
ya it looks like the Lund expression a
form

86
00:05:25,719 --> 00:05:29,719
and has gone and every do it like this
and

87
00:05:29,719 --> 00:05:33,529
it looks like the function definition

88
00:05:33,529 --> 00:05:37,199
national except that there's an arrow
here if you don't like the arrow

89
00:05:37,199 --> 00:05:40,479
you can an usually we

90
00:05:40,479 --> 00:05:44,440
we already did here am we can with the
body

91
00:05:44,440 --> 00:05:48,089
up that correctly

92
00:05:48,089 --> 00:05:51,599
we take the body and we say return

93
00:05:51,599 --> 00:05:54,830
of the expression and then in the air
and

94
00:05:54,830 --> 00:05:59,319
we can do other interesting thing so for
example we can do

95
00:05:59,319 --> 00:06:06,319
brand an that we're executing at so it
its

96
00:06:06,759 --> 00:06:09,909
we can mix and match an

97
00:06:09,909 --> 00:06:13,310
impaired if God wit higher-order
functions

98
00:06:13,310 --> 00:06:16,750
good thats

99
00:06:16,750 --> 00:06:20,180
a run our program and see if everything

100
00:06:20,180 --> 00:06:23,819
and works as advertised so

101
00:06:23,819 --> 00:06:27,339
and let's go from the top to the bottom
thats

102
00:06:27,339 --> 00:06:29,450
for surrender broke

103
00:06:29,450 --> 00:06:33,090
and then check while yes really quick

104
00:06:33,090 --> 00:06:36,280
an that the dart

105
00:06:36,280 --> 00:06:39,960
the and is really fast and the
implementation

106
00:06:39,960 --> 00:06:43,350
ellijay is extremely responsive so here

107
00:06:43,350 --> 00:06:48,300
shaper intel also on the output we
expect hello

108
00:06:48,300 --> 00:06:52,140
then we define their French in every
print af of three

109
00:06:52,140 --> 00:06:55,420
that should return for as expected

110
00:06:55,420 --> 00:06:58,650
then there's geoVax hear that and

111
00:06:58,650 --> 00:07:01,990
doubles and have a fax so

112
00:07:01,990 --> 00:07:05,260
that should be. every goal that with for

113
00:07:05,260 --> 00:07:08,590
GO FOR and goals asked

114
00:07:08,590 --> 00:07:11,620
that's five that should be done their
ego

115
00:07:11,620 --> 00:07:15,890
and now here we see that we're inside
and twice reprint

116
00:07:15,890 --> 00:07:18,940
dot dot dot and then and twice

117
00:07:18,940 --> 00:07:22,910
of and incrementing three twice gives us

118
00:07:22,910 --> 00:07:26,000
5 so that's a

119
00:07:26,000 --> 00:07:30,840
all as expected and am there's a lot of
things and art

120
00:07:30,840 --> 00:07:34,860
a that I'm didn't show

121
00:07:34,860 --> 00:07:39,350
one of the things is that dart has
classes

122
00:07:39,350 --> 00:07:44,240
an and the nice thing is starts doesn't
have a separate notion of interfaces

123
00:07:44,240 --> 00:07:47,700
its unified abstract art show there's a
less

124
00:07:47,700 --> 00:07:52,150
a syntactic baggage in languages like
Java our C sharp there's

125
00:07:52,150 --> 00:07:55,190
abstract base classes interfaces
whatever

126
00:07:55,190 --> 00:07:59,250
and art an that is

127
00:07:59,250 --> 00:08:02,560
simplified and let's go here

128
00:08:02,560 --> 00:08:05,750
at the other beautiful thing of darts

129
00:08:05,750 --> 00:08:08,800
every and go here and the

130
00:08:08,800 --> 00:08:15,800
an

131
00:08:23,270 --> 00:08:26,990
here area if we go today

132
00:08:26,990 --> 00:08:31,470
and dark language specification the dart
language specification

133
00:08:31,470 --> 00:08:36,960
is written by again not Braga a and the
same person dead roads the Java language

134
00:08:36,960 --> 00:08:38,300
specification

135
00:08:38,300 --> 00:08:42,640
an and it's a very very terrible a
description of dart

136
00:08:42,640 --> 00:08:46,930
and explains everything and the beauty
of dark here

137
00:08:46,930 --> 00:08:51,180
is that dark now an supports an

138
00:08:51,180 --> 00:08:54,770
new features a sink and and the wait

139
00:08:54,770 --> 00:08:57,830
that we are and familiar red from C
sharp

140
00:08:57,830 --> 00:09:01,600
an it also supports an

141
00:09:01,600 --> 00:09:04,770
so-called six star Matt its rich are

142
00:09:04,770 --> 00:09:07,980
and iterators that we know from
sharpened by Tong

143
00:09:07,980 --> 00:09:11,440
an and other languages

144
00:09:11,440 --> 00:09:15,160
such as PHP also support iterators an

145
00:09:15,160 --> 00:09:20,380
but it real nice thing here is dead dart
also has support for streams for a

146
00:09:20,380 --> 00:09:22,000
synchronous data streams

147
00:09:22,000 --> 00:09:25,870
an which is kind of a combination of a
single wat

148
00:09:25,870 --> 00:09:29,980
and the sink had iterator style

149
00:09:29,980 --> 00:09:34,260
programming and with these three
features I think dart

150
00:09:34,260 --> 00:09:37,740
is ahead of the game

151
00:09:37,740 --> 00:09:40,980
with respect to other and programming
languages

152
00:09:40,980 --> 00:09:44,660
an because it has full support for both

153
00:09:44,660 --> 00:09:48,800
a synchronous Matt its methods that
return synchronous collections

154
00:09:48,800 --> 00:09:52,150
and that it's that return a sickness
collection show I

155
00:09:52,150 --> 00:09:55,850
I invite you to gonna go take a look a
dart

156
00:09:55,850 --> 00:09:59,310
there's also a darts to JavaScript
compiler so

157
00:09:59,310 --> 00:10:02,570
you can print art in the regular bras
are you don't need

158
00:10:02,570 --> 00:10:06,960
the dark the an and and if you want to
write about

159
00:10:06,960 --> 00:10:11,390
applications you come from a job on or C
sharp background

160
00:10:11,390 --> 00:10:14,850
I think darts is it fantastic choice

161
00:10:14,850 --> 00:10:18,290
and thank you so much and CEO next time