Andy Gill wrote:
LINE can already refer to an external non-.hs file. This is exactly how
things works now with all manner of pre-processors, alex, happy, cpphs,
c2hs, hsc2hs, etc.
I don't quite have an intuition for this yet, can you give an example of
how this more fine grained pragma works and some use-case not currently
covered by LINE?
Ahhh. LINE does? Oh.
- GENERATED works on an expression based level, and can specify
specific spans.
(20:4 - 21:8, for example).
often LINE can be used to do this - you just have to put the expression on a
line by itself.
GENERATED would seem to be useful if the preprocessor modifies the column
numbers, not just the line numbers, of Haskell code in the original source text.
Happy is careful not to do this: we retain the indentation of the code inside
{ .. }, if I recall correctly (or if not, we should :-).
- GENERATED is a true pragma; it hints where things come from, but
does not change
the error message. I want the Haskell source spans to remain unchanges.
I don't get this - could you elaborate?
Andy - can you give us an idea of your use case for GENERATED?
If we do need this, then I suggest either {-# COL #-} for specifying the source
column number and/or {-# SPAN #-} for specifying a span (which presumably
specifies the span of the following syntactic entity, which we'd have to define
precisely).
Cheers,
Simon
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