There are two ways of using the ppx_sexp_conv
ppx rewriter:
-
the legacy way, with:
$ ocamlfind ocamlc -package ppx_sexp_conv ...
-
the new way, with a driver. Since the v0.9.0 version of
ppx_sexp_conv
one can use either theocaml-migrate-parsetree
driver orppx_driver
. Before v0.9.0 one could only useppx_driver
Using the legacy way requires using ppx_deriving
. ppx_deriving
used to be a hard dependency of ppx_sexp_conv
through
ppx_type_conv
. Since v0.9.0 it is an optional one. As a result
pacakges building using the legacy way must declare an explicit
dependency on ppx_deriving
.
Many packages didn't at the time ppx_sexp_conv
v0.9.0 was
released. To fix builds failure, a ppx_deriving
dependency was added
to all packages depending on ppx_sexp_conv
but not ppx_deriving
.
The opam tool has been separating the "build" and "install" steps of packages since version 1.2.2, but historically packages could only define a "build:" field in their metadata, that did both steps. There are many usages and tools that can benefit from the split (like tracking of installed files without losing build parallelism), and it is cleaner overall.
To upgrade older packages that didn't make the move yet, an heuristic has been
applied to automatically do the split. It's in the
admin-scripts/split-install.ml
script and simply reads commands from the end, detecting calls to install
,
cp
to appropriate destinations, and commands mentioning install
.
The main invariant to respect is that the build
stage should never write
outside of its build directory and the temp dir, while the install
stage
should be as fast as possible. So in case of doubt, it is better to put
everything in install:
instead (but we don't do that automatically, since many
correct packages only have build:
and a .install
file, which we can't detect
from the metadata alone).
In turn, opam guarantees that install
and remove
commands are never run
concurrently.
Please remember to correctly split the two stages from now on, as advised by
opam lint
; tools to check the invariants are being put in place.
Jane Street packages no longer support camlp4 after the 113.09.00 series.
For Jane Street packages that contain both a library and a camlp4 syntax extension, the latter is extracted to its own package.
The following table summarize the changes:
Package | Old findlib name of syntax | New camlp4-only package | version |
---|---|---|---|
sexplib | sexplib.syntax | pa_sexp_conv | 113.00.00 |
bin_prot | bin_prot.syntax | pa_bin_prot | 113.00.00 |
typerep | typerep.syntax | pa_typerep_conv | 113.00.00 |
fieldslib | fieldslib.syntax | pa_fields_conv | 113.00.00 |
variantslib | variantslib.syntax | pa_variants_conv | 109.15.03 |
For the long term it is recommended to switch to the corresponding ppx alternative (replace the pa_ prefix by ppx_ to get the ppx package name).
Until then packages that are using one of the camlp4 syntax extension must upgrade their build system to refer to the new package name. Simply replace the name in the second column by the one in the third column.
Running the following shell command on the sources should do:
sed -ri 's/\<sexplib\.syntax\>/pa_sexp_conv/g;
s/\<bin_prot\.syntax\>/pa_bin_prot/g;
s/\<typerep\.syntax\>/pa_typerep_conv/g;
s/\<fieldslib\.syntax\>/pa_fields_conv/g;
s/\<variantslib\.syntax\>/pa_variants_conv/g' \
`ag -l .`
The new dependency must also be added to the opam file.
To avoid the opam-repository being in a inconsistent state once the camlp4-free Jane Street packages are released, the following automatic change is applied to the opam repository:
for js_pkg in "sexplib" "bin_prot" "type_conv" "variantslib" "fieldslib":
for pkg in all_packages():
if pkg depends on js_pkg and "type_conv":
pkg.add_constraint(js_pkg < next-version-of(js_pkg))
This is an over-approximation as some package might not use the syntax extension at all.
Following this automatic change maintainers should:
- just remove the constraint if the package doesn't use the syntax extension
- do a new release that depend on the new camlp4-only package