Introduction

Sharpy is a modern, statically-typed Pythonic language targeting .NET. While Python code will not run in Sharpy without modifications, the additions and changes in Sharpy over Python should be intuitive to and welcomed by all Python developers.

Goals

• Provide a statically-typed and modern Pythonic language for the .NET CLI
• Seamless bidirectional interop with other .NET libraries
• Target C# 9.0 for maximum compatibility (Unity, .NET 5+)

Core Axioms

Sharpy's design flows from three axioms and one resolution rule. All language decisions should be predictable by applying these:

Axiom 1 — .NET Runtime: Sharpy compiles to C# 9.0 and executes on the .NET CLR. Memory model, type system, inheritance, and runtime semantics follow .NET.

Axiom 2 — Python Surface: Sharpy uses Python 3 syntax and idioms. Indentation-based blocks, keywords (True/False/None), comprehensions, decorators, and dunders come from Python.

Axiom 3 — Static & Null-Safe: Every type is statically known at compile time. None requires explicit opt-in via T?. All values must be initialized at declaration.

Resolution Rule: When Axiom 1 and Axiom 2 conflict, Axiom 1 wins, unless the compiler can reconcile them via zero-cost abstractions (naming transformations, thin wrappers, or polymorphic dispatch).

Applying the Axioms

Given any language design question, apply the axioms in order:

Question	Derivation
What is int?	Axiom 1 → System.Int32
Can I inherit from multiple classes?	Axiom 1 → No (single class, multiple interfaces)
What does len("😀") return?	Axiom 1 → 2 (UTF-16 code units)
How do closures capture variables?	Axiom 1 → By reference
Why indentation instead of braces?	Axiom 2 → Python syntax
Why does / always return a float?	Axiom 2 → Python 3 semantics
Can I use **kwargs?	Axiom 3 → No (not statically typeable)
Can a variable be uninitialized?	Axiom 3 → No
Why snake_case in source but PascalCase in .NET?	Resolution → Zero-cost naming transformation
Why do builtins like len() work on both Sharpy and .NET types?	Resolution → Zero-cost polymorphic dispatch

One-Liner Summary

Sharpy = .NET runtime + Python syntax + static null-safe types, where .NET wins conflicts unless the compiler bridges them for free.