for expressions

    Puzzler 8: Map Comprehension
    Puzzler 12: To Map, or Not to Map
    Puzzler 21: I Can Has Padding?

Java interoperability

    Puzzler 27: A Case of Strings

abstract fields

    Puzzler 4: Now You See Me, Now You Don't

abstract types

    Puzzler 28: Pick a Value, AnyValue!

anonymous functions

    Puzzler 1: Hi There!
    Puzzler 7: Caught Up in Closures
    Puzzler 35: A Listful of Dollars

case classes

    Puzzler 10: A Case of Equality

closures

    Puzzler 7: Caught Up in Closures

collections

    Puzzler 5: The Missing List
    Puzzler 12: To Map, or Not to Map
    Puzzler 25: Type Extortion
    Puzzler 31: A View to a Shill
    Puzzler 32: Set the Record Straight
    Puzzler 33: The Devil Is in the Defaults
    Puzzler 36: Size It Up

currying

    Puzzler 16: One Bound, Two to Go

default arguments

    Puzzler 16: One Bound, Two to Go
    Puzzler 19: What's in a Name?
    Puzzler 23: Adaptive Reasoning

floating-point arithmetic

    Puzzler 24: Double Trouble

function invocation

    Puzzler 6: Arg Arrgh!
    Puzzler 26: Accepts Any Args

implicits

    Puzzler 17: Implicitly Surprising
    Puzzler 29: Implicit Kryptonite
    Puzzler 30: Quite the Outspoken Type
    Puzzler 34: The Main Thing

instantiation order

    Puzzler 3: Location, Location, Location

lazy evaluation

    Puzzler 23: Adaptive Reasoning

lazy values

    Puzzler 11: If at First You Don't Succeed...

named arguments

    Puzzler 19: What's in a Name?

overloading

    Puzzler 18: Information Overload

partial application

    Puzzler 15: Count Me Now, Count Me Later
    Puzzler 17: Implicitly Surprising

pattern matching

    Puzzler 2: UPSTAIRS downstairs
    Puzzler 8: Map Comprehension
    Puzzler 27: A Case of Strings

placeholder syntax

    Puzzler 1: Hi There!

regular expressions

    Puzzler 20: Irregular Expressions

return statements

    Puzzler 14: Return to Me!

type inference

    Puzzler 6: Arg Arrgh!
    Puzzler 18: Information Overload

variable initialization

    Puzzler 2: UPSTAIRS downstairs
    Puzzler 3: Location, Location, Location
    Puzzler 4: Now You See Me, Now You Don't
    Puzzler 9: Init You, Init Me
    Puzzler 13: Self: See Self
    Puzzler 28: Pick a Value, AnyValue!
    Puzzler 34: The Main Thing