Chez Scheme REPL for Visual Studio Code

• Features and drawbacks
  • Drawbacks
• Getting started
  • Dependencies
    • Suggested Additional VS Code Extensions
  • Installation
  • Keybindings
  • Commands
  • Supported Source File Extensions
• Configuration
• VS Code Scheme specific configuration
  • My Configuration as seen in the Images
• Changes
• Contributing
• License

Features and drawbacks

• Syntax highlighting in source files and Markdown code blocks (using language identifier scheme).
• Hover with documentation of all Chez Scheme 10 identifiers (works in comments too).
• Autocompletion with documentation of all Chez Scheme 10 and local identifiers (works in comments too).
• Interactive REPL pane to the side of the editor, with commands to send code to the REPL (see Commands).
• Inline evaluation of expressions (see Commands).
• Macro expansion (see Commands).
• Checking for syntax errors on save (or by calling the command, see Commands)
• All commands available in (right-click) context menus.
• Add Keybindings

Drawbacks

• The datum comment #; only comments out until the first closing bracket. I'd rather have wrong comment syntax highlighting than no indication at all.
• Syntax highlighting of complex numbers is done in a simple way and does not recognize complex numbers with NANs or INFs.
• The REPL pane is left empty on restart of VS Code and has to be manually closed. I do not know of a way to automatically close that on exit.
• Inline evaluation can only show a single line because VA Code cannot display more than one line of a "text decoration".

Getting started

Dependencies

• Visual Studio Code version 1.65 (February 2022) or higher
• Chez Scheme.
  • Windows AMD64 GitHub Latest Release
  • MacOS Homebrew - chezscheme

Suggested Additional VS Code Extensions

• Structural editing (Paredit): Strict Paredit
• To display errors inline in the source: Error Lens

Installation

Either

• install the extension directly from the Visual Studio Code Marketplace Chez Scheme REPL
• install the extension directly from the Open VSX Registry Chez Scheme REPL
• or download the extension from the latest release at GitHub
• or build the extension yourself by cloning the GitHub Repository and running yarn install and yarn package in the root directory of the cloned repo.

Keybindings

• Inline evaluate the s-expression to the left of the cursor (command: chezScheme.evalLastSexp):
  • Windows/Linux: <Ctrl>+<Enter>
  • Mac: <Control>+<Enter> (remark: control not command!)
• Evaluate the s-expression to the left of the cursor in the interactive REPL, start it, if it isn't running (command: chezScheme.sendLastSexp)
  • Windows/Linux: <Ctrl>+<Shift>+<Enter>
  • Mac: <Control>+<Shift>+<Enter> (remark: control not command!)
• Macro-expand the s-expression to the left of the cursor in the interactive REPL, start it, if is isn't running (command: chezScheme.expandLastSexp):
  • Windows/Linux: <Alt>+<Enter>
  • Mac: <Option>+<Enter>

Commands

• Chez Scheme REPL: Start REPL (chezScheme.startREPL) - start a Chez Scheme REPL in a terminal pane to the side of the current active window.
• Chez Scheme REPL: Send selected s-expression to the REPL. (chezScheme.sendSelectionToREPL) - send the current selected s-expression to the REPL. Opens a new REPL window if no REPL is running.
• Chez Scheme REPL: Send s-expression left of the cursor to the REPL. (chezScheme.sendLastSexp) - send the s-expression to the left of the cursor to the REPL. Opens a new REPL window if no REPL is running.
• Chez Scheme REPL: Send the whole current file to the REPL (chezScheme.sendFileToREPL) - send the contents of the currently active source file to the REPL. Opens a new REPL window if no REPL is running.
• Chez Scheme REPL: Eval the selected s-expression. (chezScheme.evalSelection) - evaluate the selected s-expression and print the value inline after the selected s-expression.
• Chez Scheme REPL: Eval s-expression left of the cursor. (chezScheme.evalLastSexp) - evaluate the s-expression to the left of the cursor and print the value inline after this s-expression.
• Chez Scheme REPL: Expand all macros in the selected s-expression. (chezScheme.expandSelection) - expand all macros in the selected s-expression in the REPL. Opens a new REPL window if no REPL is running.
• Chez Scheme REPL: Expand all macros in the s-expression left of the cursor. (chezScheme.expandLastSexp) - expand all macros in the s-expression to the left of the cursor in the REPL. Opens a new REPL window if no REPL is running.
• Chez Scheme REPL: Check the current file for errors. (chezScheme.checkFile) - check the current file by loading it into the REPL. Errors are shown in the Problems tab. Called on save of a Chez Scheme file.

Supported Source File Extensions

The following list of extensions is recognized as a Chez Scheme source file:

• .ss
• .sps
• .scm
• .sch
• .sls

Configuration

• chezScheme.schemePath - Path to the Chez Scheme executable scheme. Can be either an absolute path or relative to the workspace root. Default: scheme, which works if scheme is in your PATH.
• chezScheme.replDelay - The delay in milliseconds ms to wait after starting a terminal for the interactive REPL until sending sources to it. Default: 1000ms, 1s.
• chezScheme.waiterPrompt - The string to display as an interactive REPL prompt. Default: λ>.

VS Code Scheme specific configuration

The extension adds the following Scheme specific configuration, which you can change in the settings file:

 "[scheme]": {
    "editor.insertSpaces": true,
    "editor.tabSize": 2,
    "editor.indentSize": 2,
    "editor.wordSeparators": "`()[];'\","
  }

You could also dim the bracket pair colors, but sadly only global for all file types and languages:

"workbench.colorCustomizations": {
        "editorBracketHighlight.foreground1": "#0095ff6a",
        "editorBracketHighlight.foreground2": "#cc00ff71",
        "editorBracketHighlight.foreground3": "#32833877",
        "editorBracketHighlight.foreground4": "#ff003768",
        "editorBracketHighlight.foreground5": "#6066078e",
        "editorBracketHighlight.foreground6": "#ff99008f",
        "editorBracketHighlight.unexpectedBracket.foreground": "#ff0000",
    },

My Configuration as seen in the Images

• Color theme: Bluloco Light Theme Italic
• Inline error messages: Error Lens
• Colorized brackets: enable Editor › Bracket Pair Colorization: Enabled.

 "editor.bracketPairColorization.enabled": true,

• Do not change bracket color if the bracket type changes: enable Editor › Bracket Pair Colorization: Independent Color Pool Per Bracket Type.

"editor.bracketPairColorization.independentColorPoolPerBracketType": true,

Changes

See file CHANGELOG.md.

Contributing

See file CONTRIBUTING.md

License

Chez Scheme REPL for Visual Studio Code is licensed under MIT license. See file LICENSE.

The documentation of the Chez Scheme identifiers is automatically generated from Chez Scheme Version 10 User's Guide. Chez Scheme Version 10 User's Guide is licensed under the Apache License Version 2, see https://cisco.github.io/ChezScheme/csug10.0/canned/copyright.html