I have plans to implement source maps https://github.com/eobrain/funcgo/issues/19 when targeting JavaScript

I have not yet figured out the best way to do something equivalent when targeting the JVM.

This is one of several toolchain issues. In addition to stabilizing the language itself, getting a smooth toolchain is the biggest thing left to do before a 1.0 release of Funcgo.

(Though it is worth noting that Coffeescript, an analogous language, got widespread adoption before tackling the source location issue.)