Part II Implementation of Language Features

Data dominates. If you've chosen the right data structures and organized things well, the algorithms will almost always be self-evident.

-- Rob Pike, "Notes on Programming in C"

Language syntax faces the programmer; the data layout and execution machinery behind it face the machine. This part examines the correspondence between the two: when a program contains an interface, a slice, a defer statement or a type parameter, what memory representation and execution mechanism the compiler and runtime prepare for it.

The discussion starts with the type system (Chapter 4), on which the other chapters rest. It continues with the internal representation of data structures such as strings, slices and maps (Chapter 5), the control flow of function calls, defer and panic (Chapter 6), the treatment of errors as ordinary values (Chapter 7), and how generics balance compilation speed against runtime performance (Chapter 8). With these implementations in view, the language features turn out not to be isolated syntactic conveniences but a set of interrelated engineering decisions, each with its own cost.