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FunctionSet

rlevo_evolution::function_set

Trait FunctionSet 

Source 
pub trait FunctionSet:
    Send
    + Sync
    + Debug {
    // Required methods
    fn num_functions(&self) -> usize;
    fn arity(&self, symbol: Symbol) -> usize;
    fn max_arity(&self) -> usize;
    fn apply(&self, symbol: Symbol, args: &[f32]) -> f32;
}
Expand description

The function-opcode contract shared by CGP and GEP.

Implementors describe a fixed table of functions. Each function has an arity (number of arguments) and an apply implementation that combines already-evaluated arguments into a result.

The trait is intentionally tiny: it says nothing about terminals, genome layout, or evaluation order. Callers thread a concrete &F (never &dyn FunctionSet) through their evaluation hot loops so the opcode apply inlines.

Required Methods§

Source

fn num_functions(&self) -> usize

Number of function opcodes. Their ids are 0..num_functions().

Source

fn arity(&self, symbol: Symbol) -> usize

Arity (argument count) of a function opcode.

Only meaningful for function symbols (symbol.0 in 0..num_functions()). Out-of-range ids return 0 so callers that evaluate mutated-but-unrepaired genotypes do not panic.

Source

fn max_arity(&self) -> usize

Largest arity among all functions.

Drives the GEP tail-length constraint (tail_len >= head_len * (max_arity - 1) + 1); see GepConfig::new.

Source

fn apply(&self, symbol: Symbol, args: &[f32]) -> f32

Applies a function opcode to its already-evaluated arguments.

Callers pass args.len() == self.arity(symbol). For zero-arity functions (constants such as 1.0), args is empty. Variable and constant terminals are never passed here — they are resolved by the caller’s evaluator before apply is reached.

A shorter-than-arity slice does not panic: missing arguments read as 0.0. This keeps a malformed or unrepaired genotype (runtime data) from aborting a training run, per rules.md §4.

§Numerical

apply performs raw IEEE-754 f32 arithmetic and may return a non-finite value — overflow yields ±inf, 0.0 / 0.0 yields NaN. It does not sanitize its result. Finiteness is the caller’s responsibility at two distinct layers: intermediate node values are collapsed to 0.0 for phenotype-evaluation stability (see the finite_or_zero helper), and the final fitness is mapped to −inf by the crate’s sanitize_fitness per rules.md §3.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§