Gregory Nwosu gregnwosu

I hereby claim:

To claim this, I am signing this object:

I hereby claim:

I am gregnwosu on github.
I am gregnwosu (https://keybase.io/gregnwosu) on keybase.
I have a public key whose fingerprint is 7E82 0848 D961 8907 487D 48B2 884D C0AF C389 330B

To claim this, I am signing this object:

#System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

##Basic Steps

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

	-- Vesting scheme as a PLC contract
	import Control.Monad (void, when)
	import qualified Data.Map as Map
	import qualified Data.Text as T

	import Ledger (Address, POSIXTime, POSIXTimeRange, PubKeyHash, Validator, txOutPubKey)
	import qualified Ledger
	import qualified Ledger.Ada as Ada
	import Ledger.Constraints (TxConstraints, mustBeSignedBy, mustPayToTheScript, mustValidateIn)
	import Ledger.Contexts (ScriptContext (..), TxInfo (..))

	sealed trait HList
	final case class ::[H, T <: HList](
	head: H,
	tail: T
	) extends HList
	sealed trait HNil extends HList
	case object HNil extends HNil

	object Go {
	val hlist = 10 :: "hello" :: true :: HNil

	└─[1] ./gradlew run --info --stacktrace
	Initialized native services in: /Users/greg/.gradle/native
	The client will now receive all logging from the daemon (pid: 13700). The daemon log file: /Users/greg/.gradle/daemon/4.9/daemon-13700.out.log
	Starting 38th build in daemon [uptime: 1 hrs 50 mins 59.855 secs, performance: 100%, no major garbage collections]
	Using 8 worker leases.
	Starting Build
	Settings evaluated using settings file '/Users/greg/dev/eta/eta-init/settings.gradle'.
	Projects loaded. Root project using build file '/Users/greg/dev/eta/eta-init/build.gradle'.
	Included projects: [root project 'eta-init']

	FAILURE: Build failed with an exception.

	* What went wrong:
	Problem configuring task :run from command line.
	> Unknown command-line option '--init'.

	* Try:
	Run gradlew help --task :run to get task usage details. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

	* Exception is:

	module SequenceTest where

	import Criterion.Main
	import qualified Data.Sequence as SQ

	s :: SQ.Seq Int
	s = SQ.fromList [1..9100]
	lists :: [[Int]]
	lists = replicate 10 [1..1000000]
	seqs :: [SQ.Seq Int]

	### Keybase proof

	I hereby claim:

	* I am gregnwosu on github.
	* I am gregnwosu (https://keybase.io/gregnwosu) on keybase.
	* I have a public key whose fingerprint is 7E82 0848 D961 8907 487D 48B2 884D C0AF C389 330B

	To claim this, I am signing this object:

	module ChapterExercises where

	import Data.Monoid ((<>))

	data List a =
	Nil \| Cons a (List a) deriving (Eq, Show, Ord)

	instance Functor List where
	fmap _ Nil = Nil
	fmap f (Cons a l) = Cons (f a) (f<$>l)