On Sat, 9 Jan 2016, Tobias Nipkow wrote:

One page in Concrete Semantics contains the following output that is a pretty-printed HOL formula:

step S27
(x ::= Plus (V x) (N 1) {{<x := 0>}};;
 x ::= Plus (V x) (N 2) {Q}) =
...

With db9996a84166 it prints like this:

step S27 (x ::= Plus (V x) (N 1) {{<x := 0>}};;
         x ::= Plus (V x) (N 2) {Q}) =
...

While I welcome this change(!), it seems to go against formatting in, for example, the Isabelle sources. Not an important point, just curious.

I am also curious. Are these sources easily accessible, so that I can look more closely?

Guessing from a distance, it might be the following change:

changeset:   61880:c0f34fe6aa61
user:        wenzelm
date:        Mon Dec 21 13:39:45 2015 +0100
files: src/Pure/General/pretty.ML src/Pure/General/pretty.scala src/Pure/library.scala
description:
clarified length of block with pre-existant forced breaks;


There were a number of related changes of fine points, either due to the xsymbols vs. ASCII print mode update, or due to better unification with the Poly/ML PP model. As a consequence of the latter we now also have blocks with "consistent breaks", but that feature presently unused in Isabelle syntax. The Poly/ML compiler requires that, e.g. for structures, functors, signatures.

When changing such details after 20-30 years, there is always a danger that something breaks elsewhere. So it is relevant to take another look.


        Makarius
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