How to install optional libev package for Lwt

Learning
1

I’m trying to use Lwt with the optional libev feature.
All that’s missing from my environment is the the libev library :

$ ./discover.exe -ocamlc-config ocamlc_config -lwt-config lwt_config DEBUG=y
found config var ext_obj: ...................... .o
found config var default_executable_name: ...... a.out
found config var ccomp_type: ................... cc
found config var system: ....................... macosx
found config var os_type: ...................... Unix
found config var use_libev: .................... true
testing for pkg-config: ........................ available
testing for libev: ............................. unavailable
testing for pthread: ........................... available

Some required C libraries were not found. If a C library <lib> is installed in a non-standard location, set <LIB>_CFLAGS and <LIB>_LIBS accordingly.

So I need to install libev. I downloaded the source from http://software.schmorp.de/pkg/libev.html. I was unable to find any installation instructions in the README or in the ev.pod file, so as a random guess I tried the following : ./configure followed by ./install-sh, but I get the error message ./install-sh: no input file specified What is the role of this input file I’m supposed to provide the install script with ?

2

Which platform are you using ? Can’t you install libev using your package manager ?

1 Like
3

Looks like you are on macOS. I suggest using Homebrew (or maybe MacPorts) to install libev.

For building libev from source, it looks like they are using the standard GNU build process. So, you probably need ./configure, then make, then sudo make install. But it’s much better to use Homebrew for this.

4

Thanks, that solved part of my problem, but now there are many more missing packages now (see below). However, as I am not told that those packages are required this time, I presume that I may ignore them and go ahead with the installation ?

$ ./discover.exe -ocamlc-config ocamlc_config -lwt-config lwt_config DEBUG=y
found config var ext_obj: ...................... .o
found config var default_executable_name: ...... a.out
found config var ccomp_type: ................... cc
found config var system: ....................... macosx
found config var os_type: ...................... Unix
found config var use_libev: .................... true
testing for pkg-config: ........................ available
testing for libev: ............................. available
testing for pthread: ........................... available
testing for eventfd: ........................... unavailable
testing for fd passing: ........................ available
testing for sched_getcpu: ...................... unavailable
testing for affinity getting/setting: .......... unavailable
testing for credentials getting (Linux): ....... unavailable
testing for credentials getting (NetBSD): ...... unavailable
testing for credentials getting (OpenBSD): ..... unavailable
testing for credentials getting (FreeBSD): ..... unavailable
testing for credentials getting (getpeereid): .. available
testing for fdatasync: ......................... unavailable
testing for netdb_reentrant: ................... unavailable
testing for reentrant gethost*: ................ unavailable
testing for nanosecond stat support: ........... *timespec.tv_nsec
testing for BSD mincore: ....................... available
5

Yes, this is fine. The remaining unavailable items aren’t packages, but OS features that differ between the various Unix-like OSes. Lwt will either work around each one, or compile the corresponding Lwt API to raise Lwt_sys.Not_available. The results you are getting look normal for macOS.