...well, for future reference, Invalid memory access (signal 11) at address 0x7ff7b19429f8 likely means the application has overrun its stack, especially if the stack trace shows even moderate recursion.

about the recursion though, this error happened after only 5 recursive calls (not 50,000) and that caught me off guard. i've been recently conditioned to think the stack only holds primitive values and references (pointers) but crystal, like c and similar languages, lets you pass around structures (instances of struct) by value and those values can be arbitrarily large.

now i need to figure out how to debug the contents of the stack...

#crystallang

til... the following works in #crystallang

[{1}, {2}, {3}].sort_by(&.first.-) # => [{3}, {2}, {1}]

because - is a method that returns the negative value of the number on which it is called. (the tuple in the example is obviously contrived...) this is in contrast to the following, which do the same thing but are more verbose:

puts [{1}, {2}, {3}].sort_by { |t| -t.first } 
puts [{1}, {2}, {3}].sort_by(&.first).reverse

one of the crystal programming language’s greatest strengths is the ease with which you can work with c apis and external libraries without leaving crystal. you can even implement callbacks in crystal!

in sqlite you can define new functions—callable from sql—with sqlite3_create_function by providing a name and a callback that implements the function. i created a new function called strip, entirely in crystal, that removes html markup and leaves text. it can be used in a sql query like so:

select * from objects
where strip(content) like "%term%"

it’s part of the recently released content filtering code.

#crystallang #ktistec