Tell users what they need in addition to use elm-repl

[jvoigtlaender]

People installing Elm stuff by following the directions from the README here will not currently learn about the fact that they need node.js in order to use elm-repl.

Probably:

• either that info should be added here,
• or people should be pointed to somewhere in https://github.com/elm-lang/elm-repl where that info is kept.

In addition to being told about node.js, they might also need to be told about other things (like this: #113 (comment)). So it makes sense to collect such information in only one place, but then link to that place from another place (or places).

[jvoigtlaender]

One of the other places from where people might need to be linked to a collection of "elm-repl requirements", in addition to from the README of elm-platform, might be this: https://www.npmjs.com/package/elm

[jvoigtlaender]

Refining this:

• Maybe node.js need not really be mentioned. People installing via npm will obviously already have node.js. Other people will learn about the need to install node.js as soon as they run elm-repl.
• But the stuff about libtinfo and/or ncurses should be pointed out somewhere. It came up here, and how it came up there suggests that it is not enough to mention libtinfo just in the README of https://github.com/elm-lang/elm-platform. Also, there is the issue that sometimes libtinfo seems not to be exactly the right thing. That came up for Arch Linux in the linked comment, but also for another Linux here.

[ronjouch]

@jvoigtlaender as an Elm newcomer who installed via Homepage → Install → npm installer, I confirm that I didn't hear about libtinfo requirements until bumping into this libtinfo.so.5: cannot open shared object file: No such file or directory error.

The workaround mentioned by #113 (comment) (sudo ln -s /usr/lib/libncurses++w.so.6.0 /usr/lib/libtinfo.so.5) worked for me.

Running Arch Linux, and Elm 0.16.0 on node 5.4.1 + npm 3.5.3 (official packages).

[learningjs]

Thank you @ronjouch for the solution, because not even google had helped 😸

[lacriment]

@ronjouch thank you.

[evancz]

I am reading this as, we need to tell people to install libtinfo-dev and zlib1g-dev before they build stuff. If that is correct, it is added in https://github.com/elm-lang/elm-platform#2-actually-build-elm-things now!

[jvoigtlaender]

Actually, people usually needed ncurses-dev. Whether that's covered by the other one you mention, zlib1g-dev, I don't know.

[evancz]

When I build, I believe the libtinfo-dev one covers that. If we have reports of folks building on Ubuntu or something and running into issues, I'll change it to ncurses-dev but I'm pretty sure whatever is needed is covered by the libtinfo-dev one.

[Philip-Nunoo]

@ronjouch wow you just saved me a lot of internet searching.

[dtonhofer]

If anyone drops by later:

On Fedora 27, with node v10.0.0 (compiled from source) and elm 0.18.0, elm-repl conks out with "... node/lib/node_modules/elm/Elm-Platform/0.18.0/.cabal-sandbox/bin/elm-repl: error while loading shared libraries: libtinfo.so.5".

Shared library /usr/lib64/libtinfo.so.6 is provided by package ncurses-libs-6.0 (try rpm --query --file /usr/lib64/libtinfo.so.6).

I don't know why elm-repl wants the old version (and does elm really use cabal?), but adding the symlink (cd /usr/lib64; ln -s libtinfo.so libtinfo.so.5) indeed makes elm-repl run (reliably...? we shall see)