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