layout: blog title: Explore Memoization date: 2019-07-18T16:20:16.898Z author: Toan Nguyen Gia authorAvatar: /img/uploads/t0d8dq73q-u9hr7hu1m-706d3758d60e-512.jpeg image: /img/uploads/deco-iskusstvoa-helix.jpg tags:
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layout: blog title: Explore Memoization date: 2019-07-18T16:20:16.898Z author: Toan Nguyen Gia authorAvatar: /img/uploads/t0d8dq73q-u9hr7hu1m-706d3758d60e-512.jpeg image: /img/uploads/deco-iskusstvoa-helix.jpg tags:
Latency Comparison Numbers (~2012) | |
---------------------------------- | |
L1 cache reference 0.5 ns | |
Branch mispredict 5 ns | |
L2 cache reference 7 ns 14x L1 cache | |
Mutex lock/unlock 25 ns | |
Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
Compress 1K bytes with Zippy 3,000 ns 3 us | |
Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
open Relude.Globals; | |
module R = Relude; | |
let (>>=) = IO.(>>=); | |
let fetchPostById: string => IO.t(string, string) = | |
id => | |
Fetch.fetch("https://jsonplaceholder.typicode.com/posts/" ++ id) | |
|> Js.Promise.then_(Fetch.Response.text) |
"A phantom type is a parametrised type whose parameters do not all appear on the right-hand side of its definition..." Haskell Wiki, PhantomType
The following write-up is intended as an introduction into using phantom types in ReasonML.
Taking a look at the above definition from the Haskell wiki, it states that phantom types are parametrised types where not all parameters appear on the right-hand side. Let's try to see if we can implement a similar example as in said wiki.
brew tap mopidy/mopidy
brew install mopidy
. . | |
';;,. ::' | |
,:::;,,' :ccc, | |
,::c::,,,,. :cccc, | |
,cccc:;;;;;. cllll, | |
,cccc;.;;;;;, cllll; | |
;cccc; .;;;;;;. coooo; | |
;llll; ,:::::'loooo; | |
;llll: ':::::loooo: | |
:oooo: .::::llodd: |
/* | |
* Cold observable: | |
* produce values upon each subscription | |
*/ | |
const coldObs$ = Rx.Observable.interval(1000) | |
/* | |
* Warm observable: | |
* share the value source to all subscriptions, |