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Julia: Difference between revisions
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Focus on Julia 1.6 first since that is the latest version
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(Focus on Julia 1.6 first since that is the latest version) |
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[https://julialang.org Julia] is a programming language that was designed | [https://julialang.org Julia] is a programming language that was designed for performance, ease of use and portability. It is is available as a [[Utiliser_des_modules/en | module]] on Compute Canada clusters. | ||
= Compiling packages = <!--T:3--> | = Compiling packages = <!--T:3--> | ||
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The first time you add a package to a Julia project (using Pkg.add or the package mode), the package will be downloaded, installed in <code>~/.julia</code>, and pre-compiled. The same package can be added to different projects, in which case the data in <code>~/.julia</code> will be reused. Different versions of the same package can be added to different projects; the required package versions will coexist in <code>~/.julia</code>. (Compared to Python, Julia projects replace “virtual environments” while avoiding code duplication.) | |||
From Julia 1.6 onwards, Julia packages include their binary dependencies (such as libraries). There is therefore no need to load any software module, and we recommend not to. | |||
With Julia 1.5 and earlier, you may run into problems if a package depends on system-provided binaries. For instance, [https://github.com/JuliaIO/JLD.jl JLD] depends on a system-provided HDF5 library. On a personal computer, Julia attempts to install such a dependency using [https://en.wikipedia.org/wiki/Yum_(software) yum] or [https://en.wikipedia.org/wiki/APT_(Debian) apt] with [https://en.wikipedia.org/wiki/Sudo sudo]. This will not work on a Compute Canada cluster; instead, some extra information must be provided to allow Julia's package manager (Pkg) to find the HDF5 library. | |||
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If we were to omit the <code>Libdl.DL_LOAD_PATH</code> line from the above example, it would happen to work on Graham because Graham has HDF5 installed system-wide. It would fail on Cedar because Cedar does not. The best practice on ''any'' Compute Canada system, though, is that shown above: Load the appropriate [[Utiliser_des_modules/en | module]] first, and use the environment variable defined by the module (<code>HDF5_DIR</code> in this example) to extend <code>Libdl.DL_LOAD_PATH</code>. This will work uniformly on all systems. | If we were to omit the <code>Libdl.DL_LOAD_PATH</code> line from the above example, it would happen to work on Graham because Graham has HDF5 installed system-wide. It would fail on Cedar because Cedar does not. The best practice on ''any'' Compute Canada system, though, is that shown above: Load the appropriate [[Utiliser_des_modules/en | module]] first, and use the environment variable defined by the module (<code>HDF5_DIR</code> in this example) to extend <code>Libdl.DL_LOAD_PATH</code>. This will work uniformly on all systems. | ||
= Package files and storage quotas = <!--T:7--> | = Package files and storage quotas = <!--T:7--> | ||