SlotToPOSIXTime in English Auction Demo

Question

in my cabal repl, i'm getting the following error from trying to replicate the week1 demo of Plutus-pioneer-program. I'm also unable to simulate the example scenario in the playground (i can see genesis transaction, but none of the subsequent bids), but I'm hoping the issue lies here:

Prelude Ledger.TimeSlot Week01.EnglishAuction> slotToEndPOSIXTime 10

<interactive>:10:20: error:
    • No instance for (Num SlotConfig) arising from the literal ‘10’
    • In the first argument of ‘slotToEndPOSIXTime’, namely ‘10’
      In the expression: slotToEndPOSIXTime 10
      In an equation for ‘it’: it = slotToEndPOSIXTime 10
Prelude Ledger.TimeSlot Week01.EnglishAuction> 

Answer 1

That error occurs because your code has a number literal (ie 10) in a code position where a value of type SlotCOnfig is expected and the the compiler can't figure out how to convert the literal to a SlotConfig (ie "No instance for (Num SlotConfig)").

I would need to see more of the code (possibly all of it) to figure out a solution.

Ah, so the type of slotToEndPOSIXTime is:

slotToEndPOSIXTime :: SlotConfig -> Slot -> POSIXTime

Getting a correct SlotConfig value is going to be tricky, but the good news is that Slot does have a Num instance, so the literal 10 is a valid slot.