The program "pkg-config" was not on my system. Installing it, I could at 
least continue. However now I get problems installing "camlp4". The 
compilation of "camlp4" seems to fail.

    opam install camlp4
    The following actions will be performed:
       ∗  install camlp4 4.02.0-1modular-implicits

    =-=- Gathering sources
    =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    [camlp4] Archive in cache

    =-=- Processing actions
    -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    [ERROR] The compilation of camlp4 failed at "make all".
    Processing  1/1: [camlp4: rm]
    #=== ERROR while installing camlp4.4.02.0-1modular-implicits
    ==================#
    # opam-version 1.2.2
    # os           linux
    # command      make all
    # path /home/helmut/.opam/4.02.3/build/camlp4.4.02.0-1modular-implicits
    # compiler     4.02.3
    # exit-code    2
    # env-file
    /home/helmut/.opam/4.02.3/build/camlp4.4.02.0-1modular-implicits/camlp4-31525-d2c37b.env
    # stdout-file
    /home/helmut/.opam/4.02.3/build/camlp4.4.02.0-1modular-implicits/camlp4-31525-d2c37b.out
    # stderr-file
    /home/helmut/.opam/4.02.3/build/camlp4.4.02.0-1modular-implicits/camlp4-31525-d2c37b.err
    ### stdout ###
    # [...]
    # cp
    /home/helmut/.opam/4.02.3/lib/ocaml/compiler-libs/outcometree.cmi
    camlp4/import/outcometree.cmi
    # cp /home/helmut/.opam/4.02.3/lib/ocaml/compiler-libs/oprint.cmi
    camlp4/import/oprint.cmi
    # cp /home/helmut/.opam/4.02.3/lib/ocaml/compiler-libs/toploop.cmi
    camlp4/import/toploop.cmi
    # /home/helmut/.opam/4.02.3/bin/ocamlc.opt -c -g -w Z -I
    camlp4/import -warn-error A-3 -I camlp4/config -I camlp4 -o
    camlp4/config/Camlp4_config.cmi camlp4/config/Camlp4_config.mli
    # /home/helmut/.opam/4.02.3/bin/ocamlc.opt -c -g -w a -I
    camlp4/import -warn-error A-3 -I camlp4/config -I camlp4/boot -o
    camlp4/boot/Camlp4.cmo camlp4/boot/Camlp4.ml
    # + /home/helmut/.opam/4.02.3/bin/ocamlc.opt -c -g -w a -I
    camlp4/import -warn-error A-3 -I camlp4/config -I camlp4/boot -o
    camlp4/boot/Camlp4.cmo camlp4/boot/Camlp4.ml
    # File "camlp4/boot/Camlp4.ml", line 14607, characters 36-58:
    # Error: Unbound type constructor Asttypes.implicit_flag
    # Command exited with code 2.
    # Makefile:11: recipe for target 'byte' failed
    ### stderr ###
    # + echo camlp4/Camlp4.cmo camlp4/Camlp4Top.cmo
    camlp4/camlp4prof.byte camlp4/mkcamlp4.byte camlp4/camlp4.byte
    camlp4/camlp4fulllib.cma camlp4/camlp4boot.byte
    camlp4/camlp4boot.cma camlp4/camlp4r.byte camlp4/camlp4r.cma
    camlp4/camlp4rf.byte camlp4/camlp4rf.cma camlp4/camlp4o.byte
    camlp4/camlp4o.cma camlp4/camlp4of.byte camlp4/camlp4of.cma
    camlp4/camlp4oof.byte camlp4/camlp4oof.cma camlp4/camlp4orf.byte
    camlp4/camlp4orf.cma camlp4/Camlp4Parsers/Camlp4AstLoader.cmo
    camlp4/Camlp4Parsers/Camlp4DebugParser.cmo
    camlp4/Camlp4Parsers/Camlp4GrammarParser.cmo
    camlp4/Camlp4Parsers/Camlp4ListComprehension.cmo
    camlp4/Camlp4Parsers/Camlp4MacroParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlOriginalQuotationExpander.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlParserParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlReloadedParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlRevisedParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlRevisedParserParser.cmo
    camlp4/Camlp4Parsers/Camlp4OCamlRevisedQuotationExpander.cmo
    camlp4/Camlp4Parsers/Camlp4QuotationCommon.cmo
    camlp4/Camlp4Parsers/Camlp4QuotationExpander.cmo
    camlp4/Camlp4Printers/Camlp4AstDumper.cmo
    camlp4/Camlp4Printers/Camlp4AutoPrinter.cmo
    camlp4/Camlp4Printers/Camlp4NullDumper.cmo
    camlp4/Camlp4Printers/Camlp4OCamlAstDumper.cmo
    camlp4/Camlp4Printers/Camlp4OCamlPrinter.cmo
    camlp4/Camlp4Printers/Camlp4OCamlRevisedPrinter.cmo
    camlp4/Camlp4Filters/Camlp4AstLifter.cmo
    camlp4/Camlp4Filters/Camlp4ExceptionTracer.cmo
    camlp4/Camlp4Filters/Camlp4FoldGenerator.cmo
    camlp4/Camlp4Filters/Camlp4LocationStripper.cmo
    camlp4/Camlp4Filters/Camlp4MapGenerator.cmo
    camlp4/Camlp4Filters/Camlp4MetaGenerator.cmo
    camlp4/Camlp4Filters/Camlp4Profiler.cmo
    camlp4/Camlp4Filters/Camlp4TrashRemover.cmo
    # make: *** [byte] Error 10



    =-=- Error report
    -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
    The following actions failed
       ∗  install camlp4 4.02.0-1modular-implicits
    No changes have been performed




On 03/27/2016 11:48 PM, Mohamed Iguernlala wrote:
> Hi,
>
> I guess "pkg-config" is not installed on your system. Can you confirm
> that by just trying "pkg-config --help" in a terminal ?
>
> Regards,
> Mohamed.