expressions render in user-facing syntax

[alashworth]

Issue by bob-carpenter
Thursday Aug 13, 2015 at 01:45 GMT
Originally opened as stan-dev/stan#1582

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There are still some cases that aren't working properly.

• indexing

[alashworth]

Comment by VMatthijs
Thursday Dec 13, 2018 at 13:18 GMT

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Could you clarify this issue a bit more?

[alashworth]

Comment by bob-carpenter
Thursday Dec 13, 2018 at 14:10 GMT

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We got better at this but right no we can have errors in "a * b" that get translated as "multiply(a, b)" in the error messages, even though the user never wrote "multiply". This is an issue with any kind of intermediate form normalization (* being replaced with multiply here)---we need a path back to the actual user input.

On Dec 13, 2018, at 8:18 AM, Matthijs Vákár notifications@github.com wrote:

Could you clarify this issue a bit more?

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[alashworth]

Comment by VMatthijs
Thursday Dec 13, 2018 at 15:12 GMT

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Ah right. This has been fixed in stanc3, then. It comes with a pretty printer to render an AST as Stan syntax. (Can be used for auto-formatting.) The error messages thrown by the compiler render AST nodes using this pretty printer whenever they need to refer to a node in the error. In particular, operators get rendered properly.