Intro to Golang
05 December 2016

Vincent Batts
Developer
@vbatts
vbatts@redhat.com
https://github.com/vbatts/talks

* howdy

	$> finger $(whoami)
	Login: vbatts                           Name: Vincent Batts
	Such mail.
	Plan:
	right and joyful effort
	$> id -Gn
	vbatts devel redhat oci openshift slackware docker


* golang

## Notes
# - libraries - source only, but can link to C *.so and *.a
# - Fork/Exec are coupled together (for coroutine and GC reasons)
# - Threading, and multiproc, concurrent logic
#  -- nice and easy to use
#  -- Make for tricky handling of C calls (i.e. setns)
# - `go get` is handy
# - cross-compile without hardly any bootstrapping
#  -- native compiler supported arches
#  -- gccgo works for the arch gcc is compiled for
# - primitives can seem a bit magical
#  -- conditional returns
#  -- for ... range
#  -- iota
# - no ifdefs, but build tags
# - error handling, rather than exception catching


* 

.image ./gopher.png


* Overview

- strongly typed
- compiled
- stylistically nice
- opinionated/idiomatic


* 

.image ./rainbow.jpg


* fully qualified imports

.code ./imports.go /START1/,/STOP1/


* fast compiles

(Perhaps other compilers are slow)

.play ./hello.go /START1/,/STOP1/


* defer

.code ./good0.go /START1/,/STOP1/


* Garbage Collected

- Super convenient
- references
- completed goroutines


* Garbage Collected

.link https://twitter.com/brianhatfield/status/634166123605331968 Brian Hatfield GC improvements

- go1.4 (300ms) -> go1.5 (~30ms)
- go1.6.0 (25ms) -> go1.6.3 (5ms)
- go1.7.3 (3ms) -> go1.8beta1 (sub ms on 18Gb heap)


* simple exports

.code ./good1.go /START1/,/STOP1/


* concurrency

.play ./pingpong.go /STARTMAIN1/,/STOPMAIN1/
.link http://talks.golang.org/2013/advconc.slide Sameer Ajmani - Advanced Concurrency


* 
.image ./kanye_imma_bookmarklet.png 320 _

- easy learning curve
- `go get`
- cross-compiles


* 

# they come along, and affect how you do your work
.image ./cats20.gif


* Packaging

Addresses different concern than distributions

* lack of generics?
# i don't feel strongly about this, though many do
- interfaces - are enough for most
- go1.4 introduced go:generate
# produce code for Set, Graph etc, for the types needed, but at compile time. No need to reflect.


* Debugging

- gdb is there, sort of
- some known debugging tools for ELF are not useful
- fmt.Printf("%#v\n", ...)


* Concurrency and CGO

Calls like setns(2) are rough

(yes, even with runtime.LockOSThread())

Embedding other languages (like ruby and python that have their green threading)


* Fork/Exec

Not Separate, but together


* 
.image ./revenge-of-the-nerds-o.gif


* build tags

no #ifdef

.code ./tags.go /START1/,/STOP1/

or files with *_linux.go like suffix.

More like extern.


* _

bit bucket


* channels

.play ./ugly0.go /START1/,/STOP1/


* iota

.code ./ugly1.go /START1/,/STOP1/


* for range

array (or string)

.play ./primitive1.go /START1/,/STOP1/


* for range

map

.play ./primitive2.go /START1/,/STOP1/


* for range

channel (like an iterator)

.play ./primitive3.go /START1/,/STOP1/


* for range

channel

.code ./primitive3.go /START2/,/STOP2/


* Conclusions?


* use-case

- like all languages, align with you use-case
- get familiar enough to like and dislike it
- don't be afraid to try it out