lix/doc/manual/rl-next/better-errors-in-nix-repl.md
Jade Lovelace 272db8af1b doc: add release note credits and categories for all the changes in Lix
This does not add missing release notes, and it doesn't do anything
about the profiles feature we would really like to have so we can have
consistent credit.

Change-Id: I72a6f7acfcff85f380be17dac76501a6f4693776
2024-05-15 14:33:35 -07:00

42 lines
1.1 KiB
Markdown

---
synopsis: Concise error printing in `nix repl`
prs: 9928
cls: 811
category: Improvements
credits: 9999years
---
Previously, if an element of a list or attribute set threw an error while
evaluating, `nix repl` would print the entire error (including source location
information) inline. This output was clumsy and difficult to parse:
```
nix-repl> { err = builtins.throw "uh oh!"; }
{ err = «error:
… while calling the 'throw' builtin
at «string»:1:9:
1| { err = builtins.throw "uh oh!"; }
| ^
error: uh oh!»; }
```
Now, only the error message is displayed, making the output much more readable.
```
nix-repl> { err = builtins.throw "uh oh!"; }
{ err = «error: uh oh!»; }
```
However, if the whole expression being evaluated throws an error, source
locations and (if applicable) a stack trace are printed, just like you'd expect:
```
nix-repl> builtins.throw "uh oh!"
error:
… while calling the 'throw' builtin
at «string»:1:1:
1| builtins.throw "uh oh!"
| ^
error: uh oh!
```