5 ms·

Being fluent in Python and Go, I definitely prefer the explicit error handling in Go as opposed to the try-catch error handling in python where most of the time

by joobus 9y ago

Being fluent in Python and Go, I definitely prefer the explicit error handling in Go as opposed to the try-catch error handling in python where most of the time you can never really be sure of all the possible errors which can be thrown. I spent some time learning Haskell, and one of the points that stuck was that in languages with exception handling, a function will have some kind of declared result, but all the different exceptions which can be thrown are also basically alternative return values. Any caller of the function then has to know all possible return types to effectively handle all errors, but since most code doesn't document which errors might be thrown, it's a crap shoot. Functional languages basically force the return to always be the declared type, and go mostly follows this model.

jboy 9y ago
Even though I don't like Go's explicit error handling, I think this is a very reasonable comment. I don't like Go's explicit error handling because (1) I think it clutters up your main code path with error-handling logic, and (2) it forces you to always handle errors locally (even if that local code does not have the context to know how to handle the error) or return the error code through multiple layers of functions (back to where it can be handled). That said, I completely agree that exceptions are also problematic. As you say, you can never really be sure of what exceptions can be thrown. Some languages have a "throw" keyword, in which you're meant to enumerate the list of possible exceptions; but of course, that's a headache to maintain, and is affected by inner code (such as library code) that might be completely out of your control or review. And when should the "throw" keyword be enforced, at compile time or runtime? And what should happen if the "throw" keyword's list of possible exceptions is violated? Then of course there is the other problem with exceptions, the flip-side to being forced to handle an error locally: As your exception unwinds the stack, it might obliterate some local context that is needed to decide how to handle the error; or it might obliterate some local context that is needed to continue with your original task after the error has been handled! The most interesting (and least broken) error-handling mechanism I've encountered is Common Lisp's "condition" system: http://www.gigamonkeys.com/book/beyond-exception-handling-conditions-and-restarts.html http://www.gigamonkeys.com/book/beyond-exception-handling-co... I see C++'s `std::set_new_handler` function [0] as C++'s less-capable equivalent to Lisp condition handlers. But the function invoked by `std::set_new_handler` lacks the ability to assess local context to decide how to handle the problem. [0] http://www.cplusplus.com/reference/new/set_new_handler/ http://www.cplusplus.com/reference/new/set_new_handler/ EDIT: I would love to see a language like Nim incorporate something like Lisp's condition system. Nim already offers "procedural types" (function pointers) [1] and closures [2] to capture variables from the enclosing scope. Nim even offers "anonymous procs" [3], to avoid the need to define new error-handling functions everywhere. [1] https://nim-lang.org/docs/manual.html#types-procedural-type https://nim-lang.org/docs/manual.html#types-procedural-type [2] https://nim-lang.org/docs/manual.html#procedures-closures https://nim-lang.org/docs/manual.html#procedures-closures [3] https://nim-lang.org/docs/manual.html#procedures-anonymous-procs https://nim-lang.org/docs/manual.html#procedures-anonymous-p...
- dom96 9y ago
  > That said, I completely agree that exceptions are also problematic. As you say, you can never really be sure of what exceptions can be thrown. Some languages have a "throw" keyword, in which you're meant to enumerate the list of possible exceptions; but of course, that's a headache to maintain, and is affected by inner code (such as library code) that might be completely out of your control or review. And when should the "throw" keyword be enforced, at compile time or runtime? And what should happen if the "throw" keyword's list of possible exceptions is violated? This is something that Nim offers via the `raises` pragma[1]. It is enforced at compile-time and in my experience works rather well. 1 - https://nim-lang.org/docs/manual.html#effect-system-exception-tracking https://nim-lang.org/docs/manual.html#effect-system-exceptio...
  - jboy 9y ago
    @dom96: what do you think about a Common Lisp-like "condition" system [0] in Nim? [0] http://www.gigamonkeys.com/book/beyond-exception-handling-conditions-and-restarts.html http://www.gigamonkeys.com/book/beyond-exception-handling-co...

by joobus 9y ago

jboy 9y ago

Even though I don't like Go's explicit error handling, I think this is a very reasonable comment. I don't like Go's explicit error handling because (1) I think it clutters up your main code path with error-handling logic, and (2) it forces you to always handle errors locally (even if that local code does not have the context to know how to handle the error) or return the error code through multiple layers of functions (back to where it can be handled). That said, I completely agree that exceptions are also problematic. As you say, you can never really be sure of what exceptions can be thrown. Some languages have a "throw" keyword, in which you're meant to enumerate the list of possible exceptions; but of course, that's a headache to maintain, and is affected by inner code (such as library code) that might be completely out of your control or review. And when should the "throw" keyword be enforced, at compile time or runtime? And what should happen if the "throw" keyword's list of possible exceptions is violated? Then of course there is the other problem with exceptions, the flip-side to being forced to handle an error locally: As your exception unwinds the stack, it might obliterate some local context that is needed to decide how to handle the error; or it might obliterate some local context that is needed to continue with your original task after the error has been handled! The most interesting (and least broken) error-handling mechanism I've encountered is Common Lisp's "condition" system: http://www.gigamonkeys.com/book/beyond-exception-handling-conditions-and-restarts.html http://www.gigamonkeys.com/book/beyond-exception-handling-co... I see C++'s `std::set_new_handler` function [0] as C++'s less-capable equivalent to Lisp condition handlers. But the function invoked by `std::set_new_handler` lacks the ability to assess local context to decide how to handle the problem. [0] http://www.cplusplus.com/reference/new/set_new_handler/ http://www.cplusplus.com/reference/new/set_new_handler/ EDIT: I would love to see a language like Nim incorporate something like Lisp's condition system. Nim already offers "procedural types" (function pointers) [1] and closures [2] to capture variables from the enclosing scope. Nim even offers "anonymous procs" [3], to avoid the need to define new error-handling functions everywhere. [1] https://nim-lang.org/docs/manual.html#types-procedural-type https://nim-lang.org/docs/manual.html#types-procedural-type [2] https://nim-lang.org/docs/manual.html#procedures-closures https://nim-lang.org/docs/manual.html#procedures-closures [3] https://nim-lang.org/docs/manual.html#procedures-anonymous-procs https://nim-lang.org/docs/manual.html#procedures-anonymous-p...

dom96 9y ago
> That said, I completely agree that exceptions are also problematic. As you say, you can never really be sure of what exceptions can be thrown. Some languages have a "throw" keyword, in which you're meant to enumerate the list of possible exceptions; but of course, that's a headache to maintain, and is affected by inner code (such as library code) that might be completely out of your control or review. And when should the "throw" keyword be enforced, at compile time or runtime? And what should happen if the "throw" keyword's list of possible exceptions is violated? This is something that Nim offers via the `raises` pragma[1]. It is enforced at compile-time and in my experience works rather well. 1 - https://nim-lang.org/docs/manual.html#effect-system-exception-tracking https://nim-lang.org/docs/manual.html#effect-system-exceptio...
- jboy 9y ago
  @dom96: what do you think about a Common Lisp-like "condition" system [0] in Nim? [0] http://www.gigamonkeys.com/book/beyond-exception-handling-conditions-and-restarts.html http://www.gigamonkeys.com/book/beyond-exception-handling-co...