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A Swift library for printing a breadcrumb trace on a fatal signal.
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PrettyStackTrace allows Swift command-line programs to print a trace of execution behaviors when a terminating signal is raised, such as a fatal error.

To use it, wrap your actions in a call to trace(_:). This will register an entry in the stack trace and (if your process fatal errors) will print breadcrumbs to stderr describing what was going on when you crashed.


PrettyStackTrace is available from the Swift package manager. Add

.package(url: "", from: "0.0.1")

to your Package.swift file to use it.


trace("doing first task") {
  print("I'm doing the first task!")
  trace("doing second task") {
    print("I'm doing the second task!")
    fatalError("error on second task!")

This will output:

I'm doing the first task!
I'm doing the second task!
Fatal error: error on second task
Stack dump:
-> While doing second task (func main(), in file file.swift, on line 3)
-> While doing first task (func main(), in file file.swift, on line 1)


Harlan Haskins (@harlanhaskins)

Robert Widmann (@CodaFi)


PrettyStackTrace is released under the MIT license, a copy of which is available in this repository.

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