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