ToyIDE LogoToyIDE is an imitation of a full-featured IDE plus toy languages (imperative, functional) with complete IDE support, interpreters and compilers. All the parts were built from scratch in Scala, without relying on any existing code or libraries.

The project is purely educational. It is a product of a long vacation in the country and a desire to learn how all this stuff really works.

Although I applied evolutionary design in the development (to uncover the reasons behind architecture), it turns out that many techniques in the code come close to commonly used patterns. I learned a lot from the project and hope it might be useful to the people who want to know more about lexers, parsers, AST, Java bytecode and other similar fun, but tricky things.

Update: Jason Zaugg endorsed the project as “open-source Scala application with simplicity and taste”

Source code is 100% Scala (including ~800 unit tests which run in < 3 seconds).

Download binaries: (7.5 MB)

ToyIDE: Main Window


Imperative language

Imperative, statically-typed, C-like language:

  • common data types & operators,
  • comprehensive static analysis,
  • data & control flow inspections,
  • error reporting & stack traces,
  • expression optimization,
  • JVM bytecode emitter.

Project Euler code examples:

ToyIDE: Imperative Language

Functional language

Functional, dynamically-typed, Clojure-like language:

  • macros, variadic functions,
  • quasi-quotations, anonymous function literals,
  • unique symbol name generation,
  • structural binding,
  • tail call optimization,
  • error reporting & stack traces,
  • comprehensive standard library,

Minimalistic web server code as an example:

ToyIDE: Functional Language

Syntax highlighting

Expressive syntax and error highlighting, code inspections, customizable schemes:

ToyIDE: Highlighting  ToyIDE: Coloring

Advanced editor

Editor with selection, copy/paste, undo/redo, braces balancing, auto-indentation:

ToyIDE: Edit Menu  ToyIDE: Code Menu

Split editing

Editor can be split horizontally, so that viewports, cursors and selections are separate, while text is common:

ToyIDE: Split Editing

Brace matching

Brace pairs are highlighted, complement braces are added / removed automatically:

ToyIDE: Brace Matching

Show usages

Highlighting of declaration identifier and all related references:

ToyIDE: Show Usages


Automatic completion of identifiers and keywords:

ToyIDE: Autocomplete

Code formatting

Automatic formatting of arbitrary code blocks (spacing, indentation, line breaks):

ToyIDE: Code Formatting (before)

…transformed to:

ToyIDE: Code Formatting (after)

Rename refactoring

For languages that rely on built-in concept of references, renaming works out-of-the-box:

ToyIDE: Rename Refactoring (before)

…transformed to:

ToyIDE: Rename Refactoring (after)

Control / data flow analysis

Code is checked for unused declarations and unreachable statements:

ToyIDE: Control Flow Analysis

Static code optimization

Code expressions are automatically analyzed for possible simplifications:

ToyIDE: Code Optimization

Structure pane

Internal code representation is reflected in a structure pane (with synchronous highlighting):

ToyIDE: Structure Pane


Programs can be run by interpreter, without previously compiling them into bytecode:

ToyIDE: Interpreter


Programs can also be compiled and run as JVM bytecode:

ToyIDE: Compiler

Class export

The bytecode can be exported as runnable JVM .class files:

ToyIDE: Class Export

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