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| -rw-r--r-- | Changes | 1 | ||||
| -rw-r--r-- | Upgrading | 108 |
2 files changed, 109 insertions, 0 deletions
@@ -14,6 +14,7 @@ Language: and UnixLabels. "open StdLabels" gives access to the first three. - Extended polymorphic variant type syntax, allowing union types and row abbreviations for both sub- and super-types. #t deprecated in types. +- See the Upgrading file for how to adapt to all the above changes. Type-checker: - Fixed obscure bug in module typing causing the type-checker to loop diff --git a/Upgrading b/Upgrading new file mode 100644 index 000000000..872849dd2 --- /dev/null +++ b/Upgrading @@ -0,0 +1,108 @@ + + FAQ: how to upgrade from Objective Caml 3.02 to 3.03-alpha + +I Installation + +Q1: When compiling the distribution, I am getting strange linking + errors in otherlibraries. + +A1: This is probably a problem with dynamic linking. You can disable + it with ./configure -no-shared-libs. If you really want to use + shared libraries, look in the manual pages of your system for how + to get some debugging output from the dynamic linker. + +II Non-label changes + +Q2: I get a syntax error when I try to compile a program using stream + parsers. + +A2: Stream parser now require camlp4. It is included in the + distribution, and you just need to use "ocamlc -pp camlp4o" in + place of "ocamlc". + +Q3: I get a warning when I use the syntax "#variant" inside type + expressions. + +A3: The new syntax is [< variant], which just a special case of + the more general new syntax, which allows type expressions like + [ variant1 | variant2] of [> variant]. See the reference manual + for details. + +III Label changes + +Q4: I was using labels before, and now I get lots of type errors. + +A4: The handling of labels changed with 3.03-beta. The new default + is a more flexible version of the commuting label mode, allowing + one to ommit labels in total applications. There is still a + -nolabels mode, but it does not allow non-optional labels in + applications (this was unsound). + To keep full compatibility with Objective Caml 2, labels were + removed from the standard libraries. Some labelized libraries are + kept as StdLabels (contains Array, List and String), MoreLabels + (contains Hashtbl, Map and Set), and UnixLabels. + Note that MoreLabels' status is not yet decided. + +Q5: Why isn't there a ThreadUnixLabels module ? + +A5: ThreadUnix is deprecated. It only calls directly the Unix module. + +Q6: I was using commuting label mode, how can I upgrade ? + +A6: The new behaviour is compatible with commuting label mode, but + standard libraries have no labels. You can add the following + lines at the beginning of your files (according to your needs): + open Stdlabels + open MoreLabels + module Unix = UnixLabels + Alternatively, if you already have a common module opened by + everybody, you can add these: + include StdLabels + include MoreLabels + module Unix = UnixLabels + + You will then need to remove labels in functions from other modules. + This can be automated by using the scrapelabels tool, installed + in the Objective Caml library directory, which both removes labels + and inserts needed `open' clauses (see -help for details). + $CAMLLIB/scrapelabels -keepstd *.ml + or + $CAMLLIB/scrapelabels -keepmore *.ml + Note that scrapelabels is not guaranteed to be sound for commuting + label programs, since it will just remove labels, and not reorder + arguments. + +Q7: I was using a few labels in classic mode, and now I get all these + errors. I just want to get rid of all these silly labels. + +A7: scrapelabels will do it for you. + $CAMLLIB/scrapelabels [-all] *.ml + $CAMLLIB/scrapelabels -intf *.mli + You should specify the -all option only if you are sure that your + sources do not contain calls to functions with optional + parameters, as those labels would also be removed. + +Q8: I was using labels in classic mode, and I was actually pretty fond + of them. How much more labels will I have to write now ? How can I + convert my programs and libraries ? + +A8: The new default mode is more flexible than the original commuting + mode, so that you shouldn't see too much differences when using + labeled libraries. Labels are only compulsory in partial + applications (including the special case of function with an + unkwnown return type), or if you wrote some of them. + + On the other hand, for definitions, labels present in the + interface must also be present in the implementation. + The addlabels tool can help you to do that. Suppose that you have + mymod.ml and mymod.mli, where mymod.mli adds some labels. Then + doing + $CAMLLIB/addlabels mymod.ml + will insert labels from the interface inside the implementation. + It also takes care of inserting them in recursive calls, as + the return type of the function is not known while typing it. + + If you used labels from standard libraries, you will also have + problems with them. You can proceed as described in A6. Since you + used classic mode, you do not need to bother about changed + argument order.
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