Check Prime Number - Ada-spark Typing CST Test

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Check Prime Number — Ada-spark Code

A SPARK Ada function that checks if a number is prime.

function Is_Prime(N : Natural) return Boolean is
begin
	if N <= 1 then
		return False;
	end if;
	for I in 2 .. N - 1 loop
		if N mod I = 0 then
		return False;
		end if;
	end loop;
	return True;
end Is_Prime;

Ada-spark Language Guide

SPARK is a formally verifiable subset of the Ada programming language designed for high-integrity and safety-critical systems. It enforces strong typing, design-by-contract, and static analysis to mathematically prove program correctness and eliminate entire classes of bugs.

Primary Use Cases

▸Avionics flight control software
▸Railway signaling and interlocking
▸Medical device firmware
▸Cybersecure embedded systems
▸Automotive safety ECUs

Notable Features

▸Design-by-contract with pre/postconditions
▸Strong static typing and modularization
▸GNATprove formal verification
▸Guaranteed absence of runtime errors (AoRTE)
▸High-integrity code generation support

Origin & Creator

Developed by Praxis (now Altran UK) and later extended by AdaCore, leading vendors of Ada technology for mission- and safety-critical software.

Industrial Note

SPARK is used where DO-178C Level A or IEC 61508 SIL-4 compliance is required, enabling mathematical proof of correctness for safety-critical and security-critical applications.

Quick Explain

▸SPARK is a subset of Ada that removes unsafe or ambiguous features.
▸Uses contracts (pre/postconditions, invariants) for formal correctness.
▸GNATprove tool performs static analysis and proofs.
▸Designed for avionics, medical, defense, and railway systems.
▸Guarantees freedom from runtime errors (overflow, null dereference, etc.) through proofs.

Core Features

▸Packages, procedures, functions
▸Subtype constraints and range checks
▸Contracts (pragma Assume, Assert, Post, Pre, Loop_Invariant)
▸SPARK proof annotations
▸Pure, deterministic code model

Learning Path

▸Learn Ada fundamentals
▸Understand SPARK restrictions
▸Add simple contracts
▸Use GNATprove
▸Master formal program design

Practical Examples

▸Prove array bounds safety
▸Build a verified stack ADT
▸Prove correctness of a PID controller
▸Motor controller with no runtime errors
▸Train braking logic verification

Comparisons

▸SPARK vs Ada: SPARK is the provable safe subset.
▸SPARK vs Rust: Rust focuses on memory safety; SPARK proves full correctness.
▸SPARK vs MISRA C: SPARK is more rigorous and verifiable.
▸SPARK vs SCADE: SPARK is code-level proofs; SCADE is model-based.
▸SPARK vs Eiffel: SPARK contracts are verifiable, not runtime only.

Strengths

▸Mathematical proof of correctness
▸Ultra-reliable for safety-critical domains
▸Eliminates runtime exceptions
▸Highly readable and maintainable syntax
▸Standardized and long-supported language

Limitations

▸Restricted subset compared to full Ada
▸Verification requires discipline and learning
▸Not suitable for rapid UI/desktop apps
▸Runtime features like dynamic allocation limited
▸Build times grow with extensive proofs

When NOT to Use

▸Rapid prototyping or scripting
▸Feature-rich GUIs or web apps
▸Highly dynamic memory systems
▸Non-critical hobby projects
▸Where verification costs outweigh benefits

Cheat Sheet

▸pragma SPARK_Mode(On)
▸with Pre => Condition
▸with Post => Condition
▸Loop_Invariant => Expression
▸Run: gnatprove -P project.gpr

FAQ

▸Is SPARK a separate language? -> No, a subset of Ada.
▸Can SPARK prove all logic? -> No, but proves safety properties.
▸Does SPARK allow pointers? -> Strictly controlled, mostly disallowed.
▸Can you mix Ada and SPARK? -> Yes, with boundaries.
▸Is runtime checking needed? -> Often eliminated after proofs.

30-Day Skill Plan

▸Week 1: Ada basics
▸Week 2: SPARK subset rules
▸Week 3: Contracts and subtypes
▸Week 4: GNATprove practice
▸Week 5: Verified ADTs and loops

Final Summary

▸SPARK is a verifiable subset of Ada for ultra-safe systems.
▸Used in avionics, defense, rail, and medical industries.
▸GNATprove enables mathematical correctness proofs.
▸Eliminates runtime exceptions and logic flaws.
▸Ideal where safety and reliability are non-negotiable.

Project Structure

▸src/ for code
▸gpr project file
▸spec (.ads) and body (.adb) files
▸proof annotations
▸test and harness modules

Monetization

▸Safety-critical software consulting
▸DO-178C verification services
▸Railway or avionics tool integration
▸Formal verification training
▸Certified code development

Productivity Tips

▸Write contracts early
▸Use subtypes to avoid runtime errors
▸Run proofs continuously
▸Minimize global dependencies
▸Keep procedures small and clear

Basic Concepts

▸Packages - modular code units
▸Subtypes - type-safe constraints
▸Contracts - correctness rules
▸Proof obligations - automatically generated checks
▸Abstract data types - encapsulation for safety

Official Docs

More Ada-spark Typing Exercises

Hello World in SPARK Ada Safe Division with Contracts Sum of Two Numbers Factorial Function Check Even Number Array Sum Max of Two Numbers Swap Two Numbers Simple Loop Print

Practice Other Languages

C React Python C++Rust TypeScript Kotlin PHP Java C#Ruby Mql Cql N1ql Cypher

function Is_Prime(N : Natural) return Boolean is begin if N <= 1 then return False; end if; for I in 2 .. N - 1 loop if N mod I = 0 then return False; end if; end loop; return True; end Is_Prime;