50 lines
2.3 KiB
Markdown
50 lines
2.3 KiB
Markdown
# Quickstart
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These instructions will walk you through setting up Lean using the "basic" setup and VS Code as the editor.
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See [Setup](./setup.md) for other ways and more details on setting up Lean.
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1. Install [VS Code](https://code.visualstudio.com/).
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1. Launch VS Code and install the `lean4` extension.
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1. Create a new file using "File > New File" and click the `Select a language` link and type in `lean4` and hit ENTER. You should see the following popup:
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Click the "Install Lean using Elan" link and follow the progress
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pressing ENTER in the terminal window to install lean. You should see some progress output like this:
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```
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info: syncing channel updates for 'nightly'
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info: latest update on nightly, lean version nightly-2021-12-05
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info: downloading component 'lean'
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```
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1. While it is installing you can paste the following Lean program into the new file:
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```lean
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#eval Lean.versionString
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```
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When the install finishes the Lean Language Server should start automatically and you should get a syntax-highlighting and a "Lean Infoview" popping up on the right. You will see the output of the #eval statement when
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you place your cursor at the end of the #eval statement.
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You are set up!
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## Create a Lean Project
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You can now create a Lean project in a new folder. Run `lake init foo` from the "View > Terminal" to create a package, followed by `lake build` to get an executable version of your Lean program.
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On Linux/macOS, you first have to follow the instructions printed by the Lean installation or log out and in again for the Lean executables to be available in you terminal.
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Note: Packages **have** to be opened using "File > Open Folder..." for imports to work.
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Saved changes are visible in other files after running "Lean 4: Refresh File Dependencies" (`Ctrl+Shift+X`).
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## Troubleshooting
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**The InfoView says "Waiting for Lean server to start..." forever.**
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Check that the VS Code Terminal is not prompting you with `Press ENTER key to start Lean:`. If so click in the terminal window and pressthe ENTER key.
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If that doesn't work try also running the VS Code command `Developer: Reload Window`.
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