Compat behaviours: typeof quoted expressions, macro def signatures #44
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Nice, we definitely need this!
I think a few things here should be implemented a bit differently in the longer term (AST interpolation, eval parameters (eventually hooks for eval (??))) though we could go with this more or less as-is and circle back.
There's obviously the longer term question of how expr_compat_mode should be set. My feeling is that it should eventually be a per-module configuration option that eval() reads. And that's set by some system for syntax evolution which probably relates to a package's Project.toml.
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| function interpolate_ast(::Type{Expr}, ex, values...) | ||
| Expr(interpolate_ast(SyntaxTree, ex, values...)) |
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Oh, this is a rather interesting approach. Preserving SyntaxTree in the IR as the definitive as-parsed representation is cute.
With this approach I'm concerned the logic in _interpolated_value doesn't make sense.
- When interpolating values into
SyntaxTree, we currently assumeSyntaxTreeis AST, and everything else isK"Value"(ie, a leaf) - When interpolating values into
Expr, the existing system assumesExprandLineNumberNodeare pieces of AST, and everything else is a leaf (QuoteNodeis a bit of an oddity ... is it both?)
There seems to be two ways out:
- We could take a union of all these rules and support bidirectional interpolation of Expr-into-SyntaxTree and vice versa.
- We can convert
exto anExprat lowering time then implementinterpolate_astforExprseparately.
I feel like (2) would be a good conservative option for now. But at least we should make a note about these issues.
| Expr(interpolate_ast(SyntaxTree, ex, values...)) | |
| # TODO: Adjust `_interpolated_value` to ensure that incoming `Expr` data structures are treated | |
| # as AST in Expr compat mode, rather than `K"Value"`? | |
| # Or convert `ex` to `Expr` early during lowering and implement `interpolate_ast` for `Expr`? | |
| Expr(interpolate_ast(SyntaxTree, ex, values...)) |
Co-authored-by: Claire Foster <[email protected]>
The last two major pieces needed for compatibility with existing code (that I
know of 🙂):
This is done by adding a return type parameter to
interpolate_ast, which issupplied at macro-expansion time (and in the case of
@SyntaxTree,hard-coded to
SyntaxTree).Unlike with calling old-style macros (#33), we do need a short-term way to turn
compat behaviour off. I've tied it to a a parameter to lowering that lives in
context until the end of desugaring; other suggestions are welcome.
TODO: Run most tests in both modes