Prefer statically building constants.md

imports

module Plutarch.Docs.PreferStaticallyBuilding (viacon, viaconstant) where 

import Plutarch.Prelude
import Plutarch.Api.V1.Contexts (PScriptPurpose (PMinting))
import Plutarch.Api.V1.Value (PCurrencySymbol (PCurrencySymbol))
import PlutusLedgerApi.V1 (ScriptPurpose (Minting))

Prefer statically building constants whenever possible

Whenever you can build a Plutarch constant out of a pure Haskell value - do it! Functions such as pconstant, phexByteStr operate on regular Haskell synonyms of Plutarch types. Unlike pcon, which potentially works on Plutarch terms (e.g. pcon $ PJust x, x is a Term s a). A Plutarch term is an entirely "runtime" concept. "Runtime" as in "Plutus Core Runtime". They only get evaluated during runtime!

On the other hand, whenever you transform a Haskell synonym to its corresponding Plutarch type using pconstant, phexByteStr etc. - you're directly building a Plutus Core constant. This is entirely static! There are no runtime function calls, no runtime building, it's just there, inside the compiled script.

Here's an example, let's say you want to build a PScriptPurpose - PMinting "f1e301". Which snippet, do you think, is better?

viaconstant :: Term s PScriptPurpose
viaconstant = pconstant (Minting "f1e301")
-- (or)

viacon :: Term s PScriptPurpose
viacon = let currSym = pcon $ PCurrencySymbol $ phexByteStr "f1e301"
 in pcon $ PMinting $ pdcons # pdata currSym # pdnil

The semantics are both are the same. But the former (pconstant) compiles to a constant term directly. Whereas the latter compiles to some code that builds the constant during Plutus Core runtime.

Aside: Remember that Haskell runtime is actually compile-time for Plutarch! Even if you have a dynamically computed variable in the Haskell world, it's still a constant in the Plutarch world. So you can use it just as well as an argument to pconstant!

Whenever you need to build a Plutarch term of type a, from a Haskell value, use pconstant. Whenever you need to build a Plutarch term of type PAsData a, use pconstantData!