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# Compute 100!

• gen 100 1: Generates 100 integers starting with 1.

• red *: Reduce using multiplication.

M 0.18.3 jao@loon ~/git/marcel\$ gen 100 1 | red *
93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000

# ​

• cat /usr/share/dict/words: Generate a stream of words, from /usr/share/dict/words. This uses the host executable cat.

• map (w: (len(w), 1)): For each input word, generate an output tuple containing the length of the word and the number 1.

• red . +: Group by word length, and sum up the 1s.

• sort: Sort the tuples.

M 0.18.3 jao@loon ~/git/marcel\$ cat /usr/share/dict/words \
M +\$    | map (w: (len(w), 1)) \
M +\$    | red . + \
M +\$    | sort
(1, 52)
(2, 373)
(3, 1166)
(4, 3575)
(5, 7044)
(6, 11756)
(7, 15459)
(8, 16446)
(9, 15020)
(10, 12099)
(11, 8845)
(12, 5780)
(13, 3368)
(14, 1739)
(15, 912)
(16, 399)
(17, 179)
(18, 72)
(19, 31)
(20, 10)
(21, 3)
(22, 5)
(23, 1)

Calculator

Marcel can be used as a calculator, by writing an expression inside parentheses. The command below computes the golden ratio. It is equivalent to using the map operator with a zero-function argument, i.e. map (lambda: (1 + sqrt(5)) / 2). This works because map and lambda can be omitted and are understood from context.

M 0.18.3 jao@loon ~/git/marcel\$ ((1 + sqrt(5)) / 2)
1.618033988749895

FizzBuzz

A traditional "low bar" job interview question is to implement FizzBuzz: For the integers 1 through 100, print Fizz if the number is divisible by 3, Buzz if divisible by 5, FizzBuzz if divisible by both, and the number itself otherwise. Here it is as a marcel command:

M 0.18.3 jao@loon ~/git/marcel\$ gen 100 1 \
M +\$    | map (x: 'FizzBuzz' if x % 15 == 0 else \
M +\$              'Fizz' if x % 3 == 0 else \
M +\$              'Buzz' if x % 5 == 0 else \
M +\$              x)
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
Fizz
22
23
Fizz
Buzz
26
Fizz
28
29
FizzBuzz
31
32
Fizz
34
Buzz
Fizz
37
38
Fizz
Buzz
41
Fizz
43
44
FizzBuzz
46
47
Fizz
49
Buzz
Fizz
52
53
Fizz
Buzz
56
Fizz
58
59
FizzBuzz
61
62
Fizz
64
Buzz
Fizz
67
68
Fizz
Buzz
71
Fizz
73
74
FizzBuzz
76
77
Fizz
79
Buzz
Fizz
82
83
Fizz
Buzz
86
Fizz
88
89
FizzBuzz
91
92
Fizz
94
Buzz
Fizz
97
98
Fizz
Buzz

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