Associations

$ wo '<|"Green" -> 2, "Red" -> 1|>'
<|Green -> 2, Red -> 1|>

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>'
<|Green -> 2, Red -> 1|>

Access values in associations

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; myHash[["Green"]]'
2

$ wo 'myHash = <|1 -> "Red", 2 -> "Green"|>; myHash[[1]]'
Red

$ wo 'assoc = <|"a" -> True, "b" -> False|>; assoc[["b"]]'
False

Update Values

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; myHash[["Green"]] = 5; myHash'
<|Green -> 5, Red -> 1|>

Add Values

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; myHash[["Puce"]] = 3.5; myHash'
<|Green -> 2, Red -> 1, Puce -> 3.5|>

KeyExistsQ

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; KeyExistsQ[myHash, "Red"]'
True

KeyDropFrom

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; KeyDropFrom[myHash, "Green"]'
<|Red -> 1|>

Keys

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; Keys[myHash]'
{Green, Red}

Values

$ wo 'myHash = <|"Green" -> 2, "Red" -> 1|>; Values[myHash]'
{2, 1}

Nested access

$ wo 'assoc = <|"outer" -> <|"inner" -> 8|>|>; assoc["outer", "inner"]'
8

Map

$ wo 'assoc = <|"a" -> 2, "b" -> 3|>; Map[#^2&, assoc]'
<|a -> 4, b -> 9|>