Questions re: CostModel entries

[rhyslbw]

Referring to:

ogmios/clients/TypeScript/packages/schema/src/index.ts

Lines 1250 to 1252 in 0acf18e

	export interface CostModel {
	[k: string]: Int64;
	}

1. What is the key and value here?
2. The Alonzo CDDL represents this as cost_model = [ 166*166 int ]. How does this align with the value type of Int64?

[KtorZ]

1. This map refers to the name of the Plutus-core primitives and their associate cost in abstract execution units. (see the genesis file for a list of currently existing values and their cost: https://github.com/input-output-hk/cardano-configurations/blob/master/network/mainnet/genesis/alonzo.json#L28-L193). The abstract execution units is then converted to Ada / Lovelace according to the execution prices, also in the protocol parameters (https://github.com/input-output-hk/cardano-configurations/blob/master/network/mainnet/genesis/alonzo.json#L3-L13).

2. The CDDL syntax n*m type refers to a number of occurrences in the structure. n (resp. m) being the lower (resp. upper) limit. So here, it tells us that there are exactly 166 elements in the list. Looking at the serialization code, it's also pretty clear that only the execution costs are actually serialized -- assuming a canonical ordering for deserialization; said differently, labels are omitted in the on-chain representations.