# `Monty.Runtime`
[🔗](https://github.com/d-led/ex.tbp.monty/blob/v0.1.0/packages/ex_tbp_monty_core/lib/monty/runtime.ex#L1)

What the runtime asks about a set of percepts.

Mirrors `tbp/monty/runtime.py`, which is a module of small questions rather
than a class — Monty puts them here so that every part of the system agrees on
what a step contained. The processes that *run* a model live in
`Monty.Runtime.*`; this module answers questions about the data they carry.

# `location_only_step?`

```elixir
@spec location_only_step?([Monty.Cmp.Message.t()]) :: boolean()
```

Whether no sensor module percept carries features this step.

Such a step is the sensor moving across the object without looking at it: the
sensor's position changed, so every hypothesis must move with it, but nothing
new was observed, so there is nothing to match or to learn. A learning module
uses this to displace without updating evidence.

A step with no sensor module percepts at all counts as location-only, because
the question is "did any sensor bring something to match", and none did.

Monty's `is_location_only_step`; `is_` is reserved for guards in Elixir, so
the predicate ends in `?` instead.

---

*Consult [api-reference.md](api-reference.md) for complete listing*