In F#, you can define a custom exception type by creating a type that inherit from System.Exception or using the lightweight exception syntax to define them with the same syntax as discriminated unions.
exception MyExceptionB of string
let exThrower (isA : bool option) =
match isA with
| Some(true) -> raise MyExceptionA
| Some(false) -> raise <| MyExceptionB("Blah Blah")
| _ -> raise <| new System.Exception()
| _ -> failwith "Not a valid input"
Erlang also has a number of different exception types, the most common ways to raise an exception in Erlang is via:
- error(Reason) – terminates the current process and includes a stack trace.
- exit(Reason) – similar to errors, but does not return the stack trace.
- throw(Reason) – throws exceptions that the caller can be expected to handle, also used as a way to return from deep recursion.
1> throw("Blah Blah").
** exception throw: "Blah Blah"
** exception error: boo
** exception exit: foo
In F#, you can implement a try-catch block using the try-with keywords, and it’s really easy to use pattern matching to make handling multiple types of exceptions really easy.
In Erlang, the syntax is surprisingly similar:
Another thing to keep in mind is that whilst F# has try-with and try-finally blocks there is no equivalent of C#’s try-catch-finally block. In Erlang the try-catch-finally block looks like this:
black_knight(Attack) when is_function(Attack, 0) –>
try Attack() of
_ -> "None shall pass."
throw:slice -> "It is but a scratch.";
error:cut_arm -> "I’ve had worse.";
exit: cut_leg -> "Come on you pansy!";
_:_ -> "Just a flesh wound."
io:format("Attack finished…~n", )
I specialise in rapidly transitioning teams to serverless and building production-ready services on AWS.
Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.
Check out my new course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. Including basic concepts, HTTP and event triggers, activities, callbacks, nested workflows, design patterns and best practices.
Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- Lambda optimization tip – enable HTTP keep-alive
- You are thinking about serverless costs all wrong
- Many faced threats to Serverless security
- We can do better than percentile latencies
- I’m afraid you’re thinking about AWS Lambda cold starts all wrong
- Yubl’s road to Serverless
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- AWS Lambda – compare coldstart time with different languages, memory and code sizes
- Guys, we’re doing pagination wrong