94 lines
3.5 KiB
Markdown
94 lines
3.5 KiB
Markdown
# Pantograph
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An interaction system for Lean 4.
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## Installation
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Install `elan` and `lean4`. Then, execute
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``` sh
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lake build
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```
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Then, setup the `LEAN_PATH` environment variable so it contains the library path of lean libraries. The libraries must be built in advance. For example, if `mathlib4` is stored at `../lib/mathlib4`,
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``` sh
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LIB="../lib"
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LIB_MATHLIB="$LIB/mathlib4/lake-packages"
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export LEAN_PATH="$LIB/mathlib4/build/lib:$LIB_MATHLIB/aesop/build/lib:$LIB_MATHLIB/Qq/build/lib:$LIB_MATHLIB/std/build/lib"
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LEAN_PATH=$LEAN_PATH build/bin/pantograph $@
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```
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Note that `lean-toolchain` must be present in the `$PWD` in order to run Pantograph! This is because Pantograph taps into Lean's internals.
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## Usage
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``` sh
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build/bin/pantograph MODULES|LEAN_OPTIONS
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```
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The REPL loop accepts commands as single-line JSON inputs and outputs either an
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`Error:` (indicating malformed command) or a json return value indicating the
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result of a command execution. The command can be passed in one of two formats
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```
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command { ... }
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{ "cmd": command, "payload": ... }
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```
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The list of available commands can be found in `Pantograph/Commands.lean` and below. An
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empty command aborts the REPL.
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The `Pantograph` executable must be run with a list of modules to import. It can
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also accept lean options of the form `--key=value` e.g. `--pp.raw=true`.
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Example: (~5k symbols)
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```
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$ build/bin/Pantograph Init
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lib.catalog
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lib.inspect {"name": "Nat.le_add_left"}
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```
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Example with `mathlib4` (~90k symbols, may stack overflow, see troubleshooting)
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```
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$ lake env build/bin/Pantograph Mathlib.Analysis.Seminorm
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lib.catalog
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```
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Example proving a theorem: (alternatively use `proof.start {"copyFrom": "Nat.add_comm"}`) to prime the proof
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```
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$ env build/bin/Pantograph Init
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proof.start {"expr": "∀ (n m : Nat), n + m = m + n"}
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proof.tactic {"treeId": 0, "stateId": 0, "goalId": 0, "tactic": "intro n m"}
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proof.tactic {"treeId": 0, "stateId": 1, "goalId": 0, "tactic": "assumption"}
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proof.printTree {"treeId": 0}
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proof.tactic {"treeId": 0, "stateId": 1, "goalId": 0, "tactic": "rw [Nat.add_comm]"}
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proof.printTree {"treeId": 0}
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```
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where the application of `assumption` should lead to a failure.
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## Commands
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See `Pantograph/Commands.lean` for a description of the parameters and return values in Json.
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- `reset`: Delete all cached expressions and proof trees
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- `expr.echo {"expr": <expr>}`: Determine the type of an expression and round-trip it
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- `lib.catalog`: Display a list of all safe Lean symbols in the current context
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- `lib.inspect {"name": <name>, "value": <bool>}`: Show the type and package of a
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given symbol; If value flag is set, the value is printed or hidden. By default
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only the values of definitions are printed.
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- `options.set { key: value, ... }`: Set one or more options (not Lean options; those
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have to be set via command line arguments.), for options, see `Pantograph/Commands.lean`
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- `options.print`: Display the current set of options
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- `proof.start {["name": <name>], ["expr": <expr>], ["copyFrom": <symbol>]}`: Start a new proof state from a given expression or symbol
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- `proof.tactic {"treeId": <id>, "stateId": <id>, "goalId": <id>, "tactic": string}`: Execute a tactic on a given proof state
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- `proof.printTree {"treeId": <id>}`: Print the topological structure of a proof tree
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## Troubleshooting
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If lean encounters stack overflow problems when printing catalog, execute this before running lean:
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```sh
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ulimit -s unlimited
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```
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## Testing
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The tests are based on `LSpec`. To run tests,
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``` sh
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test/all.sh
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```
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