brettrowberry

(defn isogram?
  "An isogram is a word in which no letters occur more than once.
   Empty string is considered an isogram in this implementation."
  [^String s]
  (boolean
   (when (string? s)
     (loop [letters (sort (seq s))]
       (let [[current next & _] letters]
         (cond
           (nil? next) true

brettrowberry

(System/getProperty "user.dir")

brettrowberry

debugger
#dbg
#break

brettrowberry

;; These are equivalent expressions showing how to attempt to access a value:
(get {:a \a} :a)
({:a \a} :a)
(:a {:a \a})

;; These are equivalent ways of trying and supplying a default value:
(get {:a \a} :b \b)
({:a \a} :b \b)
(:b {:a \a} \b)

brettrowberry

defaults write com.apple.Finder AppleShowAllFiles true
killall Finder

brettrowberry

// Thanks Nick Nichols
"Spy Function": {
		"prefix": "spy",
		"body": [
			"(defn spy [x] (println x) x)"
		],
		"description": "Log a value and immediately return it"
	}

brettrowberry

;; Credit, Nick Nichols
;; only tested on macOS Big Sur
(import '[java.awt.datatransfer DataFlavor StringSelection Transferable])

(defn clipboard []
  (.getSystemClipboard (java.awt.Toolkit/getDefaultToolkit)))

(defn clipboard->str
  []
  (.getTransferData (.getContents (clipboard) nil) (DataFlavor/stringFlavor)))

brettrowberry

type Faucet =
| Hot
| Cold

[<EntryPoint>]
let main _ =
    let myFaucet = Cold
    match myFaucet with
    | Cold -> 0

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<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <NoWarn>0025;</NoWarn>
  </PropertyGroup>

  <ItemGroup>
    <Compile Include="FsAdvent2020.fs" />

brettrowberry

// The 'compare' function from FSharp.Core returns a magic number to indicate the result
// compare : 'T -> 'T -> int when 'T : comparison
compare 0 1 //-1
compare 0 0 //0
compare 1 0 //1

// We could clarify our intent
type Leg = Less | Equal | Greater
type Comparer<'T> = 'T -> 'T -> Leg