Environments

Dependencies for environment implementers

Packages or code that only implement environments should depend on DrillInterface, not Drill. DrillInterface is lightweight (minimal dependencies) and provides the types and function signatures needed to implement AbstractEnv. Add Drill when you need training (PPO, SAC), parallel environment wrappers (MultiThreadedParallelEnv, BroadcastedParallelEnv), or other wrappers (e.g. NormalizeWrapperEnv). Environment validation (check_env) is provided by DrillInterface; Drill re-exports it for convenience. DrillInterface is available from the same repository as Drill.

Interface

Implement AbstractEnv with these required methods:

struct MyEnv <: AbstractEnv
    # state fields
end

DrillInterface.reset!(env::MyEnv)           # Reset to initial state
DrillInterface.act!(env::MyEnv, action)     # Take action, return reward
DrillInterface.observe(env::MyEnv)          # Return current observation
DrillInterface.terminated(env::MyEnv)       # Terminal state reached?
DrillInterface.truncated(env::MyEnv)        # Time limit reached?
DrillInterface.action_space(env::MyEnv)     # Return action space
DrillInterface.observation_space(env::MyEnv) # Return observation space

Spaces

# Continuous actions/observations
Box{Float32}(low, high)  # low/high are vectors

# Discrete actions
Discrete(n)              # Actions: 1, 2, ..., n
Discrete(n, start=0)     # Actions: 0, 1, ..., n-1

Parallel Environments

# Multi-threaded (multi-threaded, keep threading overhead in mind!)
env = MultiThreadedParallelEnv([MyEnv() for _ in 1:n_envs])

# Broadcasted (single-threaded, often fastest for cheap environments like those in ClassicControlEnvironments.jl)
env = BroadcastedParallelEnv([MyEnv() for _ in 1:n_envs])

Environment Validation

check_env(env)  # Validates interface implementation