ppr styles...

Simon Marlow simonmar at microsoft.com
Mon Sep 6 06:17:26 EDT 2004

On 06 September 2004 11:11, MR K P SCHUPKE wrote:

> Would it cause me any problems if I added "deriving Show" to all the
> types in compiler/hsSyn? (Can't think of a problem here... is there
> any reason why this is not done by default? - It is really handy if
> trying to pattern match on code syntax to be able to see what
> abstract syntax is generated by certain code)

You'll probably have to derive Show for a *lot* of types, right down to
FastString (and in fact deriving Show won't work there, you'll have to
write an instance yourself, but it shouldn't be too hard).

I guess we don't use Show because it would (a) bloat the compiler a lot,
and (b) slow down compiles, and in any case most of the time we want ppr
instead.  The Show output is going to be pretty hard to read.


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