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Cobra (programming language)
View on Wikipediafrom Wikipedia
| Cobra | |
|---|---|
| Paradigm | Multi-paradigm: object-oriented |
| Designed by | Charles Esterbrook |
| Developer | Cobra Language LLC |
| First appeared | 2006 |
| Final release | 0.9.6
/ December 23, 2013 |
| Typing discipline | strong, static, dynamic, inferred |
| OS | Microsoft .NET, Mono |
| License | MIT |
| Filename extensions | .cobra |
| Website | cobra-language |
| Influenced by | |
| Python, Eiffel, C#, Objective-C | |
Cobra is a discontinued general-purpose, object-oriented programming language.[1] Cobra is designed by Charles Esterbrook, and runs on the Microsoft .NET and Mono platforms.[2] It is strongly influenced by Python, C#, Eiffel, Objective-C, and other programming languages.[3] It supports both static and dynamic typing.[4][5] It has support for unit tests and contracts.[4] It has lambda expressions, closures, list comprehensions, and generators.[6]
Cobra is an open-source project; it was released under the MIT License on February 29, 2008.[7][8]
Features
[edit]- Object-oriented
-
- Namespaces
- Classes, interfaces, structs, extensions, enumerations
- Methods, properties, indexers
- Mixins, extension methods
- Generics, attributes
- Quality control
-
- Contracts, assertions
- Unit tests, docstrings
- Compile-time nil-tracking
- Expressiveness
-
- Static and dynamic binding
- List, dictionary, and set literals
inandimpliesoperatorforexpressions- Slicing
- Interpolated strings
- Compile-time type inference
- Lambdas and closures
- General productivity
-
- Exception handling
- Postmortem exception report
- Garbage collection
- Miscellaneous
-
- Documentation tool (
cobra -doc) - Syntax highlighting tool (
cobra -highlight)
- Documentation tool (
Examples
[edit]The following examples can be run from a file using cobra <filename>.
class Hello
def main
print 'HELLO WORLD'
A simple class
[edit]class Person
var _name as String
var _age as int
cue init(name as String, age as int)
_name, _age = name, age
def toString as String is override
return 'My name is [_name] and I am [_age] years old.'
References
[edit]- ^ "The Cobra Programming Language". Cobra Language LLC. Retrieved 2012-09-26.
- ^ Charles Esterbrook (Jan 28, 2008). Lang.NET Symposium 2008 – The Cobra Programming Language. Microsoft. Archived from the original (wmv) on March 26, 2009. Retrieved 2010-08-31.
- ^ Bridgwater, Adrian (5 March 2008). "Cobra takes a bite at open source". ZDNet UK. Retrieved 2010-08-31.
- ^ a b Neward, Ted (June 2009). "Reaping the Benefits of Cobra". MSDN Magazine.
- ^ Erickson, Jonathan (April 2008). "Was George Costanza a Computer Programmer?". Dr. Dobb's Journal.
- ^ Morris, Richard (April 2010). "Chuck Esterbrook: Geek of the Week". Simple-talk.
- ^ Krill, Paul (Feb 7, 2008). "Cobra language slithering to open source". InfoWorld. Retrieved 2010-08-31.
- ^ "The Cobra Programming Language". Cobra Language LLC. Retrieved 2008-02-29.
External links
[edit]- Official website
- The Cobra blog by Charles Esterbrook
- Cobra News Index
Cobra (programming language)
View on Grokipediafrom Grokipedia
cobra file.cobra.[1] A port to the Java Virtual Machine was in progress during its active development phase, alongside integration with IDEs such as MonoDevelop.[3]
The latest stable release, version 0.9.6, was made available on December 23, 2013, after which active development appears to have ceased, though the project remains accessible as open-source with source code and binaries for supported platforms.[6][5] Community forums and resources persist for legacy use and potential revival efforts.[7]
History
Origins and development
Cobra was designed and developed solely by Charles Esterbrook, a software consultant and language enthusiast, who began work on the project around 2006 as a personal endeavor under Cobra Language LLC.[8][9][3] The initial motivations stemmed from Esterbrook's desire to create a general-purpose language that synthesized the best attributes of existing ones, prioritizing Python's readability and simplicity for rapid development, C#'s performance on .NET platforms, and Eiffel's design-by-contract features for enhanced safety and reliability.[3][8][9] This approach aimed to address common trade-offs in programming languages, such as balancing expressiveness with execution speed and built-in quality assurances, without introducing experimental concepts.[3] Development proceeded as a self-funded effort, with Esterbrook supporting the full-time work through winnings from poker tournaments, allowing him to focus on early prototypes without external backing.[8] These prototypes evolved through iterative testing, incorporating feedback from an emerging online community via discussion forums, which influenced refinements and ultimately led to the decision to open-source the project in 2008 under the MIT license.[2][8] Key early milestones included the language's first public demonstration at the Lang.NET Symposium in early 2008, following internal beta stages that had been underway for about two years, marking the transition from private development to broader accessibility.[10][9]Release history and current status
Cobra first appeared in 2006 as a project initiated by Charles Esterbrook. It was released as open-source software under the MIT License on February 29, 2008.[2] The language progressed through a series of beta releases, beginning with version 0.7.0 on January 27, 2008, followed by version 0.8.0 in April 2008, and further iterations in the 0.9.x series, including 0.9.2 in November 2012 and 0.9.4 in May 2013.[6] These updates incorporated incremental enhancements, such as refinements to contracts and built-in unit testing support.[6] The final release, version 0.9.6, arrived on December 23, 2013, marking the end of official development.[11] After this point, activity ceased, with the last recorded commit to the primary repository occurring in March 2014.[12] As of 2025, Cobra remains discontinued, with no active development or community-driven maintenance.[13] The source code is preserved in archived repositories, such as the official GitHub mirror.[11] Binary downloads for all major releases, from 0.7.0 through 0.9.6, are available via the archived official website at cobra-language.com, supporting legacy installations on .NET 4.0+ and Mono 2.10+ platforms.[6]Design
Philosophy and influences
Cobra's philosophy revolves around synthesizing proven features from established programming languages into a cohesive, practical general-purpose language that prioritizes developer productivity, code readability, and safety without introducing experimental or overly complex elements. By blending the ease of scripting languages with the performance of compiled ones, it aims to enable quick, expressive coding while ensuring fast execution through compilation to the .NET and Mono platforms.[14] Central tenets include a strong emphasis on quality-driven development, achieved via language-level support for contracts, unit tests, and compile-time error checking such as nil tracking, which reduces runtime bugs and promotes robust applications. Cobra balances flexibility and discipline by supporting both static typing for performance-critical code and dynamic typing for rapid prototyping, allowing developers to choose approaches that suit their needs. It also defaults to accurate decimal mathematics to avoid common floating-point pitfalls, further enhancing reliability.[15][14] The language draws significant influences from Python, adopting its indentation-based syntax for clean, symbol-light code structure and simplicity in everyday programming tasks. C# shapes Cobra's object-oriented features, generics, and seamless integration with the .NET ecosystem, while Eiffel's design-by-contract approach informs its built-in preconditions, postconditions, and invariants for verifiable software correctness. Objective-C contributes concepts around messaging and dynamic dispatch, and Ruby adds to the focus on expressiveness; other minor influences include Visual Basic for certain declarative elements and Smalltalk for object-oriented purity.[16][15][14] Key design goals encompass minimizing boilerplate through concise syntax for common operations like properties and collections, elevating testing and contracts to first-class language constructs for inherent quality assurance, and incorporating lightweight metaprogramming via mixins and extensions without the overhead of more intricate systems. This philosophy positions Cobra as a bridge between scripting convenience and enterprise-grade development, fostering productivity across diverse applications from prototypes to high-performance software.[14][15]Syntax overview
Cobra source files use the .cobra extension.[1] The language employs indentation to structure code blocks, following a Python-like approach where each level of indentation consists of either one tab character or four spaces, but mixing tabs and spaces within the same line triggers a compiler error.[1] Core keywords includeclass for declaring classes, def for defining methods, init for constructors (declared as def init), var for variable declarations (which support dynamic typing when no type is specified), and control flow elements such as if, else, and for for loops.[17][1]
Statements end at newlines, rendering semicolons optional and rarely used. Single-line comments begin with #; multi-line comments and documentation strings use triple quotes """.[17][18] Strings are enclosed in single or double quotes and support interpolation via embedded expressions in square brackets, such as 'Hello, [_name]'.[17]
Cobra programs require a main method within a class, typically declared as class Program def main is shared, to serve as the entry point, with all executable code contained within classes and methods rather than at the top level. The language supports shebang lines (e.g., #!/usr/bin/env cobra) for scripting, enabling direct execution of .cobra files as standalone scripts.[1][19]
Relative to its influences, Cobra's syntax demands more verbosity than Python for explicit type declarations (e.g., var x as String) but achieves greater conciseness than C# by relying on indentation over mandatory braces and semicolons.[3]
Language features
Typing system
Cobra features a hybrid typing system that defaults to static typing for enhanced performance, compile-time error checking, and type safety, while offering dynamic typing through thedynamic keyword to enable flexibility in scenarios requiring late binding or polymorphic behavior.[20] This approach allows developers to leverage the benefits of both paradigms without fully committing to one, as static types facilitate optimization and early detection of incompatibilities, whereas dynamic types support rapid prototyping and integration with varying data sources.[19]
Type inference plays a central role in the static typing model, automatically deducing variable types from initialization expressions to minimize explicit annotations and improve code readability. For instance, a local variable assigned an integer literal, such as n = 10, is inferred as the int type and remains fixed thereafter, preventing reassignment to incompatible types like strings at compile time.[1] This inference applies to local variables within methods, reducing boilerplate while maintaining static guarantees, though explicit type declarations like n as int = 10 are available for clarity or when initialization is deferred using the var keyword, as in var n as int.[17]
The language enforces strong typing, prohibiting implicit conversions between incompatible types to uphold safety and prevent subtle runtime bugs. Numeric operations, for example, require matching types or explicit casts, and attempts to mix strings with numbers without coercion result in compile-time errors under static contexts.[18] Supported primitive types include bool for logical values, string for text, char for single characters, and numeric variants such as decimal for exact fractional arithmetic, float32 and float64 for approximate floating-point, and number as a built-in type that defaults to decimal.[21] Object types encompass classes, interfaces, and enums, while built-in collections like lists, sets, and dictionaries are supported through generic types (e.g., List<of string>) and literal syntax for concise initialization.[3]
Binding in Cobra is static by default for explicitly declared or inferred types, resolving method calls and property accesses at compile time for efficiency. However, dynamic binding occurs for variables or parameters marked with dynamic, such as in def process(x as dynamic), where operations like x.someMethod() are resolved at runtime, enabling duck typing for unknown or heterogeneous inputs.[19] Late-bound calls, including those on dynamic entities, defer resolution to execution, which can invoke .NET reflection under the hood for interoperability.[20]
Error handling aligns with the typing mode: static contexts perform rigorous compile-time checks for type mismatches, unreachable code, and invalid assignments, often reporting multiple issues simultaneously to accelerate development.[18] In contrast, dynamic contexts shift type-related errors to runtime, where exceptions arise from failed method resolutions or invalid operations, such as invoking a nonexistent property on a dynamic object; this trades early detection for adaptability but may increase debugging overhead.[20] This duality integrates with Cobra's design-by-contract features to enhance overall type safety without overlapping into precondition enforcement.[19]
Design by contract
Cobra's design by contract system draws directly from the Eiffel programming language, incorporating preconditions to ensure conditions hold before method execution, postconditions to verify outcomes afterward, and invariants to maintain class-wide state consistency throughout an object's lifecycle.[22] This approach promotes reliable software by embedding behavioral specifications directly into the code, allowing developers to define expectations that the compiler and runtime can enforce. In Cobra, preconditions are specified using therequire keyword followed by one or more boolean expressions, such as require serialNum > 0, which must evaluate to true prior to method invocation; failure triggers a RequireException. Postconditions employ the ensure keyword, often referencing the method's return value with result (e.g., ensure result > 0) or pre-execution state via the old prefix (e.g., .actionCount == old .actionCount + 1), ensuring post-execution validity and raising an EnsureException if violated. Class invariants, declared with invariant (e.g., .serialNum >= 1000), apply to the entire object and are checked at method entry and exit, with violations throwing an InvariantException. These contracts attach to methods or classes and are verified at runtime by default, though they can be disabled via the compiler flag cobra -contracts:none to avoid overhead in production environments.[22]
The system supports inheritance by allowing subclasses to extend contracts with or require for preconditions or and ensure for postconditions, ensuring derived classes uphold or strengthen the base specifications. Benefits include early error detection during development and testing, clear documentation of method interfaces, and facilitated maintenance through explicit behavioral guarantees. However, runtime checks introduce performance overhead, which can be mitigated by omitting them in release builds.[22]
Built-in unit testing
Cobra's built-in unit testing framework allows developers to embed tests directly within class definitions, promoting close proximity between code and its validations. Tests are declared using thetest keyword, followed by a block containing one or more assert statements that verify expected behaviors. For instance, within a class, a test block might examine method outputs or exception handling, such as expecting a NullArgumentException for invalid inputs. This syntax integrates seamlessly with Cobra's object-oriented structure, treating tests as first-class elements akin to methods or properties.[23][19]
The framework supports automatic discovery of all test blocks within a class or project during execution. Assertions provide detailed failure reporting, including the evaluated subexpressions, source file, line number, and relevant object state, which aids in rapid debugging. Additionally, the expect keyword extends testing to anticipated exceptions, ensuring robust error handling validation. Tests can leverage Cobra's contracts—such as require and ensure clauses—for combined runtime and explicit checks, though unit tests focus on discrete validations rather than ongoing enforcement. This integration fosters a layered approach to quality assurance without requiring separate tooling.[23][15]
To execute tests, developers use the built-in Cobra compiler with the -test option, such as cobra -test MyClass.cobra, which compiles the code, runs the tests, and provides pass/fail summaries. For broader project testing, the command scans and runs all discovered tests across files, reporting results in a concise format. This runner is included in the standard Cobra tools, eliminating the need for external frameworks like NUnit or JUnit. In production builds, tests can be excluded via the -turbo flag to optimize deployment.[19][24]
The philosophy behind Cobra's testing emphasizes ubiquity and simplicity, encouraging tests as executable documentation that evolves with the codebase. By embedding tests inline, developers reduce context-switching and dependency on disparate tools, aligning with Cobra's goal of quality-driven development. A typical workflow involves writing test blocks alongside new methods during implementation, then invoking the test runner as part of the compilation process to validate changes iteratively. This approach not only catches regressions early but also serves as living examples for team members, enhancing maintainability in medium- to large-scale projects.[3][23]
Advanced constructs
Cobra provides several advanced language constructs that enable expressive and efficient programming, drawing from functional and object-oriented paradigms to support concise code generation and reuse. Lambdas in Cobra are anonymous functions defined using thedo keyword, allowing for inline function definitions that can capture variables from their enclosing scope, thus forming closures. This feature facilitates functional-style programming, such as passing small functions to higher-order methods for tasks like sorting or filtering collections. For example, a lambda might be used as sort list using do (a, b) a > b, where the closure captures external variables if needed.[25][3]
List comprehensions, known as "for expressions" in Cobra, offer a declarative way to transform iterables, similar to those in Python. The syntax is for var in sequence [where condition] get expression, producing a new collection. An example is lengths = for s in strings get s.length, which creates a list of string lengths from an input list of strings. These expressions support optional filtering with where clauses, such as outstanding = for cust in customers where cust.balance > 0 get cust, enhancing readability for data transformations.[26]
Generators enable lazy evaluation of sequences through the yield keyword, allowing functions to produce a series of values on demand without storing the entire result in memory. This is particularly useful for iterating over large or infinite datasets, such as recursive structures. Cobra's how-to guide includes examples of using yield to traverse recursive data, integrating seamlessly with for loops and other iteration constructs.[27]
Mixins in Cobra provide a mechanism for composing behavior across classes, functioning as trait-like additions that support multiple inheritance without resolving the diamond problem at runtime—all handled via compile-time composition. A class can incorporate a mixin using the mixins keyword in its declaration, inheriting methods and properties to promote code reuse and modularity. For instance, a Logger mixin might add logging methods to any class that includes it, reducing duplication while maintaining single inheritance for the primary class hierarchy.[25][3]
Exception handling in Cobra follows a structured approach with try-catch blocks, allowing developers to anticipate and manage runtime errors gracefully. The syntax includes try for protected code, catch clauses for specific exception types (e.g., catch ex as IOException), and an optional finally for cleanup. This integrates with Cobra's compile-time nil tracking to minimize unexpected exceptions, as demonstrated in examples handling database or file operations.[1][24]
Modules in Cobra are supported through multi-file compilation, where related source files (e.g., .cobra files) are built together into a single assembly, enabling modular organization without explicit import statements for local modules. Access to external .NET libraries occurs via namespace declarations, such as use System.IO, facilitating integration with the broader ecosystem. This approach simplifies dependency management while leveraging the compiler to resolve references across files.[18]
Implementation
Compiler and tools
The Cobra compiler is a command-line tool namedcobra that processes source files with the .cobra extension and generates Microsoft Intermediate Language (IL) bytecode as .NET assemblies, such as executables (.exe) or libraries (.dll). This output is compatible with the .NET runtime and can be consumed by other .NET languages like C# or VB.NET. The tool supports direct execution of source files for scripting-like workflows, where cobra filename.cobra compiles and runs the program in one step, leaving behind the compiled assembly for reuse.[1][15]
The compilation process begins with parsing the source code, followed by semantic analysis including static type checking for declared types and contract verification. Cobra's hybrid typing system allows dynamic resolution at runtime for undeclared types, but the compiler enforces checks for obvious mismatches, such as assigning a string to an integer variable, issuing errors before code generation. Contracts and built-in unit tests are evaluated where possible during this phase to catch violations early. The final step emits optimized IL bytecode. To compile without immediate execution, developers use flags like -c or -compile, producing standalone assemblies runnable directly on Windows or via Mono on Unix-like systems. The -turbo flag activates full optimizations and removes debug symbols for production builds.[1][18][19]
Error reporting emphasizes compile-time diagnostics, providing clear messages for issues like inconsistent indentation (e.g., mixing tabs and spaces) or contract failures. These diagnostics include line numbers, expected versus actual types, and suggestions for resolution, aiding rapid debugging. Runtime errors for dynamic aspects are handled via .NET exceptions, but the compiler's proactive checks reduce their occurrence.[1][18]
For IDE support, legacy plugins like VisualCobra provided syntax highlighting and project integration in Visual Studio 2010, though full compiler invocation required command-line fallback.[28]
Cobra's build system is straightforward and makefile-like, relying on the cobra tool for single-file or multi-file compilation without a dedicated package manager. Developers typically use simple scripts or .NET build tools like NAnt for larger projects, compiling modules into assemblies that reference each other via standard .NET mechanisms. This approach prioritizes simplicity over complex dependency resolution. The compiler targets .NET and Mono platforms for broad compatibility, as detailed in the supported platforms section.[19]
Supported platforms
Cobra runs primarily on the Microsoft .NET Framework for Windows environments and on Mono for cross-platform support, enabling execution on Linux and macOS.[25] This reliance on the Common Language Runtime (CLR) ensures compatibility with .NET 4.0 or later on Windows and Mono 2.10 or equivalent on Unix-like systems.[11] The language offers full integration with the .NET ecosystem, permitting Cobra code to directly invoke C# libraries and other .NET assemblies without additional bridging mechanisms.[24] However, Cobra does not support native compilation; instead, its compiler generates intermediate language (IL) code that is executed via the CLR's just-in-time (JIT) compilation process.[1] This approach introduces runtime overhead from dynamic typing and other features, though it leverages the CLR's optimized execution environment for overall performance.[4] Key limitations include its tight coupling to the CLR, which precludes support for mobile platforms or WebAssembly targets.[11] As of 2025, Cobra remains a legacy language with no official ports to modern .NET versions such as .NET Core or .NET 5 and later; it functions on .NET Framework 4.x installations but requires maintenance for contemporary environments.[25]Examples
Hello World program
The simplest program in Cobra, often referred to as "Hello World," demonstrates the language's basic syntax for outputting text to the console. This can be written as a top-level script without requiring a class definition, leveraging Cobra's scripting conveniences for quick execution.[21] Here is the basic example saved in a file namedhello.cobra:
cobra
print 'Hello, world.'
print 'Hello, world.'
print statement to output the string literal 'Hello, world.' to the standard console. String literals in Cobra are enclosed in single or double quotes, and the print function handles the display without additional formatting. Top-level execution allows statements like this to run directly when the file is processed by the Cobra compiler, providing a Python-like simplicity for introductory scripts. Indentation is not required for this single statement, though it denotes structure in more complex code.[1][21]
To compile and run the program, use the Cobra compiler from the command line: cobra hello.cobra. This single command compiles the source to an executable (typically hello.exe on .NET platforms) and runs it immediately, producing the output "Hello, world." On Windows with .NET, the executable runs natively; on Unix-like systems with Mono, it may require mono hello.exe if not run via the compiler. For a variation enabling direct scripting, add a shebang line at the top of the file:
cobra
#!/usr/bin/env cobra
print 'Hello, world.'
#!/usr/bin/env cobra
print 'Hello, world.'
chmod +x hello.cobra and run it directly as ./hello.cobra, allowing seamless integration as a script on Unix-like systems.[1][21]
Simple class definition
In Cobra, classes are declared using theclass keyword followed by the class name, establishing a blueprint for objects that encapsulate data and behavior. All members, such as variables and methods, are public by default unless specified otherwise.[17]
A simple class definition might look like the following example for a Person class, which stores a name and provides a string representation:
cobra
class Person
var _name as String
cue init(name as String)
_name = name
def toString as String
return 'Name: ' + _name
class Person
var _name as String
cue init(name as String)
_name = name
def toString as String
return 'Name: ' + _name
_name of type String using var, which underscores Cobra's static typing system where parameter and variable types must be explicitly specified.[17] The constructor, named init and introduced with the cue keyword, initializes the object with a required name parameter; it assigns the value directly to the instance variable. The toString method, defined with def, returns a formatted string using concatenation (+ operator) and explicitly declares its return type as String.[29][1]
To use this class, an instance is created and methods invoked as shown:
cobra
p = [Person](/page/Person)('Alice')
print p
p = [Person](/page/Person)('Alice')
print p
Person object with the name "Alice" and outputs "Name: Alice" by implicitly calling toString during printing. Such definitions highlight Cobra's object-oriented foundations, blending concise syntax with compile-time type safety.[17]