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6.7 REPL & Packages in Julia


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 Example

Julia REPL Help Pages (local)

  • Type "?" to enter help pages within REPL

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

Julia REPL Help Example

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>

  • To see REPL history

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

Using Packages

julia> using CSV
		julia> using DataFrames

		julia> exit()


  • 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