I have two nested loops like this: loop1 do ... loop2 do ... break if cond ... end ... end Here, the break just gets me out of the inner loop2 but I want to get out of both. I have a cludge way of doing that, but does Crystal provide an elegant way to break out of both?

Another way to do it is to leverage the ability for break/loop to return a value. E.g. loop do b = loop do break true if true end break if b end Similar to your flag example, but a bit more concise/robust.

Yeh, but the desire is to not use two break points.

As I stated above, a method, and then using return is the easiest way to accomplish that. def mark_nonprimes(nonprimes, residues, val, md, bitn, kmax) breakpoint = Math.isqrt(val) nonprimes.each_with_index do |resgroup, k|# for each kth residue group residues.each_with_index do |prime_re…

Thanks for your example. But again, I don’t want to make the code more complex. It’s clear there’s no simple(r) way to break out of nested loops than to use nested breaks, or my original code that only created one loop to break out of.

Maybe someone from core team can speak to why throw/catch from Ruby was not added to Crystal.

[image] Throw and catch So, most of all familiar with throw and catch thing in Ruby. It’s sometimes useful to be able to break away from a deep-leveled stack. And raising a error is quite expensive. Why isn’t it in the language yet? Also related: throw and catch with…

I suppose this could be solved with throw/catch but really a more direct solution would be a nesting value for break. In PHP for example, you can pass a number to break which determines how many nested levels of loops it should break. throw/catch is often critizised for pulling code out of context …

I was never a big fan of the pass the number of loops to break out of approach, it seems too easy to mess up when moving code around and encourages deep loop nesting in the first place. I’m also unsure how well it fits and interacts with the fact that Crystal loops are really just repeatedly called …

There’s also the thing that if we allow breaking from an inner loop then we need to think about how the type inference/flow changes. All type inference done up until the “break” point is carried over outside, which makes the compiler and the language harder to implement and understand.

[image] straight-shoota: I suppose this could be solved with throw / catch but really a more direct solution would be a nesting value for break . In PHP for example, you can pass a number to break which determines how many nested levels of loops it should break. break can be extended, without…

Elegant breaking from nested loops

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Blacksmoke16 February 8, 2022, 2:08pm 11

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Elegant breaking from nested loops

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