Go Notes

Iain Haslam
17 February 2017
Subjects: go
Home page

The Go project includes … a cultural agenda of radical simplicity.

“The Go Programming Language”, Donovan and Kernighan.

These are my notes while learning Go. It's mostly things I might forget, or which I'm likely to have to refer to.

I don't expect this to be helpful to anyone else; if you're starting out, the tour is great.

Once you've finished the tour, you'll find that the specification is brief and easily readable - you can complete the whole thing in maybe five hours. It may be useful to know before you begin that the spec starts from individual language elements before working through the methods of bringing those elements together. The result is that the first complete program appears around 95% of the way through; but by the time you get there, you should understand every line of it.

There's also this Go Cheatsheet which you'd probably prefer.

Videos

Rob Pike - What was wrong with the old integer 80?
Rob Pike - Origins of Go Concurrency Style
Rob Pike - Concurrency is not Parallelism

Recall

Only functions named with initial capitals are exported from packages
defer pushes function call onto LIFO stack, to be called at end of current function (not enclosing block). “Defer, Panic, Recover”

Trivial syntax reminders

const like C, but declare multiple consts in one-per-line lists (like imports)
for i := 0; i < 10; i++ {} … like C; no (); happily with enforced {}
for i < iterations {} … init and post optional as C - no semicolons if both omitted
for {} … ∞ loop - still no semicolons
if x < 0 {} - again no (). Python meets C, also in simple multiple return values
if v := math.Pow(x, n); v < lim { … if has optional init
switch like C, without fallthrough (look, no breaks!), cases can be non-const and any type.
p := &i (for instance var p *int = &i) pointers as C (*p = 42), without pointer arithmetic
Dereferencing a field (*p).X is simplified to p.X (i.e. not p->X)
type Vertex struct - otherwise like C: v := Vertex{1, 2}, v.X = 1.1
var a [10]int array syntax, otherwise like C …
… with slices of Python (nothing fancy like step, and unlike Python, altering the slice alters the original - it's referencing memory) a[3:8], a[:8], a[8:]
len(s) for slices as Python
cap(s) for capacity of underlying slice (distance from start of slice to end of underlying)
Looping over range (slice/map) returns index and copy of element: for i, v := range myslice { }
Skip index: for _, v := range
Skip element: for v := range
Maps:
make: m := make(map[string]int)
insert: m["answer"] = 42
retrieve: elem, ok := m["question"] - not present, ok is false
delete: delete(m, key)

Methods, not classes

Videos

Recall

Trivial syntax reminders

Types