6.7 REPL & Packages in Julia

Documentation

• Julia Cheat Sheet (see REPL and Package Management)

• Julia REPL

• Julia Pkg

• Packages

  • CSV.jl

  • DataFrames.jl

Using REPL

• Interactive command-line REPL (read-eval-print loop)

• Allows for quick and easy evaluation of Julia statements

• Includes dedicated help ? and shell modes ;

Julia REPL Example (local)

• Type "julia" in terminal to launch REPL

Julia REPL Help Pages (local)

• Type "?" to enter help pages within REPL

• Type a function from Julia to read help pages (ex: println)

Practice with this web-based Julia REPL

Installing Packages

• Start Julia REPL by typing the following in Terminal or PowerShell (Note: do not need to type $ - this is to indicate the shell prompt)

$ julia

• Go into REPL mode for Pkg, Julia’s built in package manager, by pressing ]

$ julia ]

$ (@v1.4) pkg>

• Update package repository in Pkg REPL

$ (@v1.4) pkg> update

• Add packages in Pkg REPL

$ (@v1.4) pkg> add CSV

$ (@v1.4) pkg> add DataFrames

• Check installation

(@v1.4) pkg> status
            Status `~/.julia/environments/v1.0/Project.toml`
                [336ed68f] CSV v0.4.3
                [a93c6f00] DataFrames v0.17.1
                ...

• Get back to the Julia REPL and exit by pressing backspace or ^C.

(@v1.4) pkg>

julia>

• To see REPL history

$ more ~/.julia/logs/repl_history.jl

Using Packages

julia> using CSV
		julia> using DataFrames

		julia> exit()

Troubleshooting

• If you get an error like: ERROR: SystemError: opening file "C:\\Users\\User\\.julia\\registries\\General\\Registry.toml": No such file or directory

  • Delete C:\\Users\\User\\.julia\\registries where User is your computer’s username and try again

  • https://discourse.julialang.org/t/registry-toml-missing/24152