Raito Bezarius
e1f5a981ef
It's 2026 and the command handler was entirely manual! We introduce a basic command handler framework for the REPL that handles all the previous (implicit) features reasonably well. This also builds up the infrastructure for nicer features. Most important feature is that now we can let external plugins adds commands to the REPL. There's slight REPL changes: - errors for debugger commands are more explicit. - short-hand have a long-hand version. - help shows command sorted by std::map natural key sorting (based on aliases) while keeping the special syntaxes for the REPL language at the top. - sections were introduced for Flakes commands. - :st was merged into one command with an optional argument marker. Change-Id: Ibd24f994491bf5d45d4b218fd84c0944ae5050fd Signed-off-by: Raito Bezarius <raito@lix.systems>
113 lines
3.9 KiB
Plaintext
113 lines
3.9 KiB
Plaintext
@args --debugger
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:c at the root repl is not allowed since no debugger is running yet
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nix-repl> :c
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error: command 'c' can only be used when the debugger is active
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:c and other commands become available once a debugger starts
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nix-repl> with {}; a
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> :?
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The following commands are available:
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<expr> Evaluate and print expression
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<x> = <expr> Bind expression to variable
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:?, :help Print help about all commands (this content)
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:a, :add <expr> Add attributes from resulting set to scope
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:b, :build <expr> Build a derivation
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:bl, :build-with-gc-roots <expr> Build a derivation, creating GC roots in the working directory
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:doc <expr> Show documentation for the provided function (experimental lambda support)
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:e, :edit <expr> Open package or function in $EDITOR
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:env Show environment stack
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:i, :build-and-install <expr> Build derivation, then install result into current profile
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:l, :load <path> Load Nix expression and add it to scope
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:log <expr | .drv path> Show logs for a derivation
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:p, :print <expr> Evaluate and print expression recursively
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Strings are printed directly, without escaping.
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:q, :quit Exit the REPL
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:r, :reload Reload all files successfully loaded
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:sh, :shell <expr> Build dependencies of derivation, then start nix-shell
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:t, :type <expr> Describe result of evaluation
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:te, :trace-enable [bool] Enable, disable, or toggle showing traces for errors
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:u, :use <expr> Build derivation, then start nix-shell
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Debug mode commands
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:bt, :backtrace Show trace stack
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:c, :continue Go until end of program, exception or builtins.break
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:s, :step Go one step
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:st, :show-trace [integer index] Show current trace. If an integer is provided, this switches to that stack beforehand.
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Flakes commands
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:lf, :load-flake <flakeref> Load Nix flake and add it to the scope
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we can now inspect state
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nix-repl> :bt
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0: error: undefined variable 'a'
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«string»:1:10
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1| with {}; a
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| ^
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1: error: Fake frame for debugging purposes
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«string»:1:10
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1| with {}; a
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| ^
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and resume execution
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nix-repl> :c
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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the debugger is once again disabled
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nix-repl> :c
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error: command 'c' can only be used when the debugger is active
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leaving the debugger from a toplevel error and entering it again doesn't leave old frames visible
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nix-repl> with {}; a
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> :s
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error: undefined variable 'a'
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at «string»:1:10:
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1| with {}; a
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| ^
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nix-repl> with {}; b
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error: undefined variable 'b'
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at «string»:1:10:
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1| with {}; b
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| ^
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nix-repl> :bt
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0: error: undefined variable 'b'
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«string»:1:10
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1| with {}; b
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| ^
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1: error: Fake frame for debugging purposes
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«string»:1:10
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1| with {}; b
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| ^
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exiting from here prints the error
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nix-repl> :q
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error: undefined variable 'b'
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at «string»:1:10:
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1| with {}; b
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| ^
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