Hello. Thank you!
I updated the Crystal code for catalan numbers with the product method ;) and the anagrams code using response.body.
Yes, anagrams works fine now. 
Addition:
FYI, you can also just use one factorial method, which improves performance.
def factorial(n)
(1..n).product(1.to_big_i)
end
user system total real
catalan_direct 0.000000 0.000062 0.000062 ( 0.000057)
catalan_rec1 0.090235 0.000000 0.090235 ( 0.090260)
catalan_rec2 0.000003 0.000000 0.000003 ( 0.000002)
1 Like
Mon 2020/4/6
Weird numbers
https://rosettacode.org/wiki/Weird_numbers#Crystal
@jzakiya, coulld you please run the benchmark on your laptop, please
1 Like
The first 25 weird numbers are: 70 836 4030 5830 7192 7912 9272 10430 10570 10792 10990 11410 11690 12110 12530 12670 13370 13510 13790 13930 14770 15610 15890 16030 16310
0.031349 0.007468 0.038817 ( 0.030550)
Addition:
It’s more idiomatic to write short if statements as one-liners, eg:
if i != j
divs2 << j div2 << j if i !=j
end
2 Likes
Mon 2020/4/6
I’ve listed (currently 44) all the Crystal Rosetta Code examples posted here. These have been updated as necessary, to work with versions >= 0.31 which changed from doing / to // for integer math, etc. As newer versions come out, they should continue to be updated to remain current, so having them in a list like this makes it easier to do that.
I think it would be a great idea for the website to have a page that lists all the Rosetta Code examples (including those not posted here) in one place, so users (potential, new, et al) can see tangible examples of how Crystal is used to do real things. I’m even willing to maintain such a page, if no one else is.
What do you think? 
9 billion names of God the integer (Tu 2020/3/26)
https://rosettacode.org/wiki/9_billion_names_of_God_the_integer#Crystal
Ackermann function (Tu 2020/3/26)
https://rosettacode.org/wiki/Ackermann_function#Crystal
AKS test for primes (Fri 2019/3/29)
https://rosettacode.org/wiki/AKS_test_for_primes#Crystal
Anagrams (Mon 2020/4/6)
https://rosettacode.org/wiki/Anagrams#Crystal
Anti-primes (Mon 2020/4/6)
https://rosettacode.org/wiki/Anti-primes#Crystal
Averages/Root Mean Square (Fri 2019/3/29)
https://rosettacode.org/wiki/Averages/Root_mean_square#Crystal
Benford’s law (Fri 2020/3/13)
https://rosettacode.org/wiki/Benford’s_law#Crystal
Bernoulli numbers (F 2019/4/26)
https://rosettacode.org/wiki/Bernoulli_numbers#Crystal
Best shuffle (Sun 2019/4/28)
https://rosettacode.org/wiki/Best_shuffle#Crystal
Binary digits (F 2019/4/26)
https://rosettacode.org/wiki/Binary_digits#Crystal
Binary search (Wed 2019/5/22)
https://rosettacode.org/wiki/Binary_search#Crystal
Catalan numbers (Mon 2020/4/6)
https://rosettacode.org/wiki/Catalan_numbers#Crystal
Combinations and permutations (Tu 2019/4/16)
https://rosettacode.org/wiki/Combinations_and_permutations#Crystal
Combinations with repetitions (Tu 2019/4/16)
https://rosettacode.org/wiki/Combinations_with_repetitions#Crystal
Fast Fourier Transform (Fri 2019/3/29)
https://rosettacode.org/wiki/Fast_Fourier_transform#Crystal
Farey sequence (Sat 2019/3/23).
https://rosettacode.org/wiki/Farey_sequence#Crystal
Gamma function (Th 2019/5/9)
https://rosettacode.org/wiki/Gamma_function#Crystal
Generate random chess position (Fri 2019/5/3)
https://rosettacode.org/wiki/Generate_random_chess_position#Crystal
Harshad or Niven series (Mon 2019/4/1)
http://rosettacode.org/wiki/Harshad_or_Niven_series#Crystal
Haversine formula (Mon 2019/4/1)
https://rosettacode.org/wiki/Haversine_formula#Crystal
Hickerson series of almost integers (Tu 2019/4/16)
https://rosettacode.org/wiki/Hickerson_series_of_almost_integers#Crystal
Jaro distance (Mon 2019/4/22)
https://rosettacode.org/wiki/Jaro_distance#Crystal
Jortsort (Tu 2019/4/23)
https://rosettacode.org/wiki/JortSort#Crystal
Josephus problem (Tu 2019/4/23)
https://rosettacode.org/wiki/Josephus_problem#Crystal
Julia Set (Fri 2019/3/29)
https://rosettacode.org/wiki/Julia_set#Crystal
Leonardo Numbers (Mon 2019/4/1)
https://rosettacode.org/wiki/Leonardo_numbers#Crystal
Levenshtein distance (Mon 2019/4/1)
https://rosettacode.org/wiki/Levenshtein_distance#Crystal
Lucas-Lehmer test (Sat 2020/4/4)
https://rosettacode.org/wiki/Lucas-Lehmer_test#Crystal
Luhn test of credit card numbers (W 2020/4/1)
https://rosettacode.org/wiki/Luhn_test_of_credit_card_numbers#Crystal
Lychrel numbers (Sat 2020/4/4)
https://rosettacode.org/wiki/Lychrel_numbers#Crystal
Miller-Rabin primality test (Wed 2019/3/19)
https://rosettacode.org/wiki/Miller–Rabin_primality_test#Crystal
Modular exponentiation (Sun 2020/3/29)
https://rosettacode.org/wiki/Modular_exponentiation#Crystal
Modular inverse (Fri 2020/3/6)
https://rosettacode.org/wiki/Modular_inverse#Crystal
Monte Carl methods (Sat 2020/4/4)
https://rosettacode.org/wiki/Monte_Carlo_methods#Crystal
N’th (Mon 2019/3/25)
https://rosettacode.org/wiki/N’th#Crystal
Pythagorean quadruples (Fri 2019/5/3)
https://rosettacode.org/wiki/Pythagorean_quadruples#Crystal
Pythagorean triples (Fri 2019/5/3)
https://rosettacode.org/wiki/Pythagorean_triples#Crystal
Quick Select (Tu 2020/3/26)
https://rosettacode.org/wiki/Quickselect_algorithm#Crystal
Roots of Unity (Fri 2019/3/29)
https://rosettacode.org/wiki/Roots_of_unity#Crystal
Runge Kata (Fri 2019/3/29)
https://rosettacode.org/wiki/Runge-Kutta_method#Crystal
Sierpinski carpet (Tu 2019/4/23)
https://rosettacode.org/wiki/Sierpinski_carpet#Crystal
Sum of a series (Th 2019/4/19)
https://rosettacode.org/wiki/Sum_of_a_series#Crystal
Sum multiples of 3 and 5 (Th 2019/4/19)
https://rosettacode.org/wiki/Sum_multiples_of_3_and_5#Crystal
Weird numbers (Mon 2020/4/6)
https://rosettacode.org/wiki/Weird_numbers#Crystal
5 Likes
I think it’s a great idea.
I could help maintaining that page, too
3 Likes
FASTA format (Fri 2020/4/11)
3 Likes
Hi @orangeSi, welcome to the club!
May I make some suggestions, and give you some tips, on getting your code to work.
I copied your code and ran it and it didn’t compile/run because of some coding errors, and structural deficiencies. These can be easily corrected though.
First a quick Tip.
Replace the markup as below to get keyword color highlighting Rosetta Code has for Ruby, to make the code look prettier.
=={{header|Crystal}}== -> =={{header|Crystal}}==
<lang crystal> <lang ruby>
Now for the code.
A person should be able to copy the shown source code, put it in a file and run it, and get the output shown for the example. There’s one clear code formatting error in the example, an unconnected trailing } in the last line, which creates a compiling syntax error.
A structural code deficiency is it doesn’t provide the required test input strings. A means to provide the strings needs to be added in order to create the required output. You can view the Ruby example to see one way to do this.
https://rosettacode.org/wiki/FASTA_format#Ruby
Finally, to make the code look more idiomatic Crystal, make short if conditions one-liners (not 3), which I mentioned in a few post before this one. Also, it’s more idiomatic to use 2 spaces for indentations, and not tabs, to show code hierarchy.
Always run your code to test it, before submitting it.
So if you put the code in a file, for example called fasta.cr, you should be able to run it and get the required output, as: $ crystal fasta.cr
Once the code is working correctly we can put in on the list as another task done. 
1 Like
M 2020/4/13
Factors of a Mersenne number
https://rosettacode.org/wiki/Factors_of_a_Mersenne_number#Crystal
Thanks~ I changed it to ruby so that crystal code have the highlight now ~
1 Like
Wed 2020/4/15
Primality by trial division
https://rosettacode.org/wiki/Primality_by_trial_division#Crystal
Sequence of primes by trial division
https://rosettacode.org/wiki/Sequence_of_primes_by_trial_division#Crystal
Thanks~ I changed to one-line and use 2 spaces instead of tab, and add crystal playground url to header for test the code.
Able to run it in on playground, copied to a file and ran as $ crystal fasta.cr too.
Great job! 
I will add it to the list. Keepm cumin!
3 Likes
Th 2020/4/16
Fermat numbers
https://rosettacode.org/wiki/Fermat_numbers#Crystal
This is a good example of leveraging the GNU/Linux coreutils library in Crystal efficiently.
2 Likes
Sat 2020/4/18
Happy numbers
https://rosettacode.org/wiki/Happy_numbers#Crystal
This is the 50th task posted in this thread so far!! 
In addition: Number 51
Random numbers
https://rosettacode.org/wiki/Random_numbers#Crystal
5 Likes
Sun 2020/4/19
Cumulative standard deviation
https://rosettacode.org/wiki/Cumulative_standard_deviation#Crystal
I can do this using a class|object but not the Ruby (et al) version using a lambda. Does Crystal have the equivalent? Is there a (short) direct translation of code below?
def sdaccum
n, sum, sum2 = 0, 0.0, 0.0
lambda do |num|
n += 1
sum += num
sum2 += num**2
#Math.sqrt( (sum2 / n) - (sum / n)**2 )
Math.sqrt( (sum2 * n - sum**2) / n**2 )
end
end
sd = sdaccum
[2,4,4,4,5,5,7,9].each {|n| print sd.call(n), ", "}
1 Like
I think you could use Proc
https://crystal-lang.org/reference/syntax_and_semantics/literals/proc.html
1 Like
I’ve tried every technique from the docs using procs before giving up and asking for help. I’ve exhausted my limit of ideas, but I’m still curious if Crystal can do it this way too.
That’s literally just replacing lambda do |num| with ->(num : Int32) do. Makes me wonder what you tried :)
Not that I think this is a pretty solution btw…
1 Like
Hey thanks @jhass, I knew it had to be something simple.
All I had to use was the Crystal Programming Language:
https://crystal-lang.org/reference/
https://crystal-lang.org/reference/syntax_and_semantics/blocks_and_procs.html
There’s nothing there that even mentions/references lambdas or compatibility w/Ruby. In fact, putting lambda in the page search bar returns: No results matching "lambda"
Now that I know the syntax, I can translate more of the Ruby examples that use explicit lambdas, so this was a successful learning exercise for me.
Are there other online references that do a better|more thorough job of explaining (w/examples) how to use Crystal, especially for people coming from primarily Ruby?