Stacky ☆ BEAM stack trace in Gleam

a stack trace of stack frames with module name, function name, arity, file name and line number

Best used with pprint.

gleam add stacky
gleam add pprint

Usage

import pprint
import stacky

pub fn main() {
  let stack =
    stacky.trace()
    // See the strack trace:
    |> pprint.debug

  let frame =
    stack
    |> stacky.frame(0)
    // See the top most stack frame, from this call site:
    |> pprint.debug

  frame
  |> stacky.gleam_module_name
  // See the current module name, from this call site:
  |> pprint.debug

  frame
  |> stacky.function_name
  // See the current function name, from this call site:
  |> pprint.debug

  // prints gleam module.function and erlang with line number to stdout
  frame |> stacky.print_frame_ln
}

stdout:

StackTrace([
  StackFrame(
    ErlangModuleName("stacky"),
    FunctionName("main"),
    FunctionArity(0),
    ErlangFileName("stacky/build/dev/erlang/stacky/_gleam_artefacts/stacky.erl"),
    ErlangLineNumber(202),
  ),
  StackFrame(
    ErlangModuleName("stacky@@main"),
    FunctionName("run"),
    FunctionArity(1),
    ErlangFileName("stacky/build/dev/erlang/stacky/_gleam_artefacts/stacky@@main.erl"),
    ErlangLineNumber(11),
  ),
  StackFrame(
    ErlangModuleName("erl_eval"),
    FunctionName("do_apply"),
    FunctionArity(7),
    ErlangFileName("erl_eval.erl"),
    ErlangLineNumber(746),
  ),
  StackFrame(
    ErlangModuleName("init"),
    FunctionName("start_it"),
    FunctionArity(1),
    ErlangFileName([
      110, 111, 45, 102, 105, 108, 101,
    ]),
    ErlangLineNumber(-1),
  ),
  StackFrame(
    ErlangModuleName("init"),
    FunctionName("start_em"),
    FunctionArity(1),
    ErlangFileName([
      110, 111, 45, 102, 105, 108, 101,
    ]),
    ErlangLineNumber(-1),
  ),
  StackFrame(
    ErlangModuleName("init"),
    FunctionName("do_boot"),
    FunctionArity(3),
    ErlangFileName([
      110, 111, 45, 102, 105, 108, 101,
    ]),
    ErlangLineNumber(-1),
  ),
])
StackFrame(
  ErlangModuleName("stacky"),
  FunctionName("main"),
  FunctionArity(0),
  ErlangFileName("stacky/build/dev/erlang/stacky/_gleam_artefacts/stacky.erl"),
  ErlangLineNumber(202),
)

"stacky"

"main"

stacky.main - arity: 0 - erlang file: stacky/build/dev/erlang/stacky/_gleam_artefacts/stacky.erl:202

Demo

gleam run -m stacky/internal/sub_dir/example_in_sub_dir.gleam

Further documentation can be found at https://hexdocs.pm/stacky.