Sims City

Academic project developed as part of my PAF (Programmation Avancée en style Fonctionnel) at STL Master — Sorbonne Université

A SimCity-inspired city-builder game built entirely in Haskell, where the player constructs and manages a living city on a top-down grid. The simulation runs in real time, managing individual citizen lifecycles — including immigration, work, rest, hunger, and emigration — while the player balances economy, pollution, safety, and infrastructure.

🛠️ Tech Stack

• Core Technologies: Haskell, SDL2 (rendering & input), SDL2-TTF (font rendering), Linear (vector math)
• Tools & Environment: Stack (build & dependency management), HSpec (unit testing), QuickCheck (property-based testing), PQueue (A* pathfinding), Cabal

📦 Installation & Setup

Prerequisites

• GHC — Glasgow Haskell Compiler
• Stack — Haskell build tool
• libsdl2-dev — SDL2 system library (v2.0+)
• libsdl2-ttf-dev — SDL2 TTF extension

Linux / Ubuntu:

sudo apt install libsdl2-dev libsdl2-ttf-dev

macOS (Homebrew):

brew install sdl2 sdl2_ttf

Windows: Install msys2 (automatically configured by Stack), then:

stack exec -- pacman -S mingw-w64-x86_64-SDL2 mingw-w64-x86_64-SDL2_ttf

⚠️ SDL2 is currently not compatible with Apple M1 chips.

Instructions

# 1. Clone the repository
git clone https://github.com/Tinshea/Sims_City.git
cd Sims_City

# 2. Build the project
stack build

# 3. Run the game
stack run

# 4. (Optional) Run the test suite
stack test

🎮 Gameplay

The game runs on a 1920×1080 top-down grid. Using the Tools panel (top-right), the player places infrastructure by spending money, and monitors key city metrics in real time.

🏗️ Buildable Infrastructures

Infrastructure	Size	Cost	Description
Residential Zone	70×70	$100	Houses citizens. Contains up to 4 buildings (shacks or houses). Collects rent.
Commercial Zone	70×70	$100	Contains 4 grocery stores. Citizens shop here to restore hunger.
Industrial Zone	70×70	$100	Contains 4 workshops. Citizens earn a salary of $200 per work cycle.
Road	30×30	$10	Required adjacency for all zones. New roads must connect to existing ones.
Energy Plant	70×70	$500	Powers adjacent zones. Increases pollution by +50 units.
Wire	—	$5	Conducts electricity from energy plants to distant zones.
Police Station	70×70	$100	Increases city safety by +1 per station within 500px of residential/commercial zones.

📊 City Metrics

Metric	Description
Money	Earned via taxes and rent. Spent on infrastructure.
Population	Total number of citizens currently in the city.
Pollution	Increases near industrial zones (+10) and energy plants (+50).
Safety	Improves with police stations near residential/commercial zones.

👥 Citizen Lifecycle

Citizens go through three distinct states:

Immigrant ──(zone available)──► Citizen ──(broke / starving / exhausted)──► Emigrant ──► expelled

• Immigrants spawn at a rate of 1% per tick (1–20 at a time) when pollution is low, safety is sufficient, and population is under 100.
• Citizens are each assigned one residential, one industrial, and one commercial building. Their state (money, hunger, fatigue) updates every 100 ticks.
• Emigrants are expelled from the city every tick. Citizens become emigrants when money = 0, hunger = 0, or fatigue = 0.

Citizen Behavior Loop

Occupation	Trigger	Effect
Travailler	Default	+$200, −5 hunger, −10 fatigue
Shopping	Hunger < 20	Moves to grocery store, +20 hunger/tick
Dormir	Fatigue < 20	Moves to residence, +20 fatigue/tick
Move	Changing destination	Travels toward target zone

🗂️ Project Structure

Sims_City/
├── app/              # Entry point (Main.hs)
├── src/              # Core game logic
│   ├── Ville.hs      # City model, citizen lifecycle, A* pathfinding, economy
│   └── Shapes.hs     # Geometric types (Coord, Forme, Zone, Batiment)
├── test/             # HSpec unit tests & QuickCheck properties
│   ├── VilleSpec.hs  # Tests for city operations
│   └── ShapesSpec.hs # Tests for geometric primitives
├── assets/           # Game sprites and fonts (Minecraft-inspired)
├── package.yaml      # Stack package manifest
└── stack.yaml        # Stack resolver & dependency config

✅ Testing

The project uses two complementary testing strategies:

• HSpec unit tests — cover core operations: route connectivity, zone collision, power supply (isPowered), citizen updates, A* pathfinding, building placement, pollution calculation, and all geometric predicates.
• QuickCheck property tests — define invariants and pre/post-conditions for all key types (Ville, Citoyen, Zone, Batiment, Forme, Coord) and operations.

stack test

⚠️ Some QuickCheck properties (prop_isPowered, prop_updateCitizens, prop_invariant_creer_imigrant) are defined but currently failing and require further adjustment.

⚙️ Key Dependencies

Package	Role
sdl2	Window management, rendering, event handling
sdl2-ttf	TrueType font rendering
linear	2D vector & coordinate math
containers	Maps and sets for city state
random	Stochastic immigrant generation
pqueue	Priority queue for A* pathfinding
hspec	Unit testing framework
QuickCheck	Property-based testing

👤 Authors

• Malek Bouzarkouna — 28706508
• Paul Mekhail — 28708078

Sorbonne Université — Master STL, 2024

📄 License

Distributed under the BSD3 License. See LICENSE for details.