Wiki: Crystal

General

Some tricks that work in Ruby also work in Crystal. Some don't. Crystal has some tricks of its own, of course!

Iteration

(0..9).map{}  # returns an array
10.times{}  # returns nil
0.to 9{}   # also returns nil, but very short. always better than the previous line
("0".."9").map{}  # could occasionally be useful

String manipulation

• Crystal's string gsub method can do more than Ruby's. You can call it with just a block, and the block doesn't have to return a string.

"123abcABC".gsub{|c|c.ord}  # "495051979899656667"

• Sadly, Crystal doesn't have Ruby's * overload for joining arrays of strings. But, Crystal's array join method can take a block and transform each item before joining.

[1, 2, 3].join{|x| 2*x}  # "246"

eval

• If you find yourself missing Ruby's eval, rejoice: Crystal has eval too! You can write in a command literal,

`crystal eval "#{your code string here}"`

to eval your troubles away. Will that ever be good for golf? I don't know. If you want to use eval, you might want to use macros instead?