Go 101 jobandtalent.com, November 2015 Álex González

Some history Designed by: Robert Griesemer, Rob Pike & Ken Thompson 6 years ago At Google To improve C++ And because they hated it

Why Go? Asynchronous concurrency as part of the language Compiled to a single binary Garbage collected Fast Go tools!

Why NOT Go? Libraries not always as mature, but improving! No generics... is that a real problem? Dependency management

Your first program p a c k a g e m a i n i m p o r t " f m t " f u n c m a i n ( ) { f m t . P r i n t l n ( " H i w o r l d ! " ) } Run

Hands on!

types { u , } i n t { , 8 , 1 6 , 3 2 , 6 4 } f l o a t { 3 2 , 6 4 } c o m p l e x { 6 4 , 1 2 8 } b o o l b y t e r u n e "Code point" in Unicode (item represented by a single value). s t r i n g

More types a r r a y s An array type definition specifies a length and an element type. s l i c e s A slice is a data structure describing a contiguous section of an array stored separately from the slice variable itself. A slice is not an array. A slice describes a piece of an array. m a p s Key/value storage.

Moarrrrr types s t r u c t s p o i n t e r s f u n c t i o n s i n t e r f a c e s t y p e j o b A n d T a l e n t s t r u c t { e m p l o y e e s i n t } f u n c m a i n ( ) { j t : = j o b A n d T a l e n t { e m p l o y e e s : 2 , } f m t . P r i n t l n ( j t . e m p l o y e e s ) } Run

THE Type c h a n "A channel can be imagined to be a pipe or a conveyer belt of a defined size and capacity. On one side one can place an item onto this imaginary conveyer belt and on the other side one can take it."

Let's the magic begin

Your second program p a c k a g e m a i n f u n c m a i n ( ) { v a r s s t r i n g = " h i " / / N o t s t y l i s h e n o u g h f o r v e t v a r s 2 s t r i n g s 2 = " t h e r e " v a r s 3 = " j o b a n d t a l e n t " s 4 : = " f o l k s " p r i n t l n ( s , s 2 , s 3 , s 4 ) } Run

Named errors v a r N a m e d E r r o r = e r r o r s . N e w ( " I s t h i s a n e x c e p t i o n ? " ) f u n c b r e a k S o m e t h i n g ( ) e r r o r { r e t u r n N a m e d E r r o r } f u n c m a i n ( ) { e r r : = b r e a k S o m e t h i n g ( ) s w i t c h e r r { c a s e N a m e d E r r o r : l o g . P r i n t l n ( " F a i l e d a s e x p e c t e d " ) d e f a u l t : l o g . P a n i c ( " I d i d n ' t e x p e c t t h i s ! " ) } i f e r r : = b r e a k S o m e t h i n g ( ) ; e r r = = N a m e d E r r o r { l o g . P r i n t l n ( " T h i s f a i l e d a s e x p e c t e d a s w e l l ! " ) } } Run

JSON t y p e P e r s o n s t r u c t { N a m e s t r i n g ` j s o n : " n a m e " ` } f u n c m a i n ( ) { v a r s e n t P e o p l e = [ ] P e r s o n { P e r s o n { " M i h a i " } , P e r s o n { " A l e x " } } p a y l o a d , e r r : = j s o n . M a r s h a l ( s e n t P e o p l e ) i f e r r ! = n i l { l o g . P a n i c ( e r r ) / / D o n ' t d o t h i s a t h o m e } f m t . P r i n t l n ( s t r i n g ( p a y l o a d ) ) v a r r e c e i v e d P e o p l e [ ] P e r s o n i f e r r : = j s o n . U n m a r s h a l ( p a y l o a d , & r e c e i v e d P e o p l e ) ; e r r ! = n i l { l o g . P a n i c ( e r r ) } f o r _ , p : = r a n g e r e c e i v e d P e o p l e { f m t . P r i n t l n ( p . N a m e ) } } Run

Type switch f u n c o u t p u t ( w h a t e v e r i n t e r f a c e { } ) { s w i t c h v : = w h a t e v e r . ( t y p e ) { c a s e s t r i n g : f m t . P r i n t l n ( " A S t r i n g : " , v ) c a s e i n t : f m t . P r i n t l n ( " S o m e i n t : " , v ) d e f a u l t : f m t . P r i n t l n ( " I d o n ' t k n o w w h a t t y p e i s t h i s o n e : " , v ) } } f u n c m a i n ( ) { o u t p u t ( " t h i s i s s o m e t e x t " ) o u t p u t ( 1 ) o u t p u t ( 1 . 1 ) } Run

The good one about interfaces! t y p e D e v e l o p e r i n t e r f a c e { L i k e s D e v e l o p m e n t ( ) b o o l } t y p e ( G o o d D e v s t r u c t { } M e r c e n a r y D e v s t r u c t { } ) f u n c ( M e r c e n a r y D e v ) L i k e s D e v e l o p m e n t ( ) b o o l { r e t u r n f a l s e } f u n c ( G o o d D e v ) L i k e s D e v e l o p m e n t ( ) b o o l { r e t u r n t r u e } f u n c C o u l d W o r k H e r e ( d D e v e l o p e r ) b o o l { r e t u r n d . L i k e s D e v e l o p m e n t ( ) } f u n c m a i n ( ) { f m t . P r i n t l n ( C o u l d W o r k H e r e ( G o o d D e v { } ) , C o u l d W o r k H e r e ( M e r c e n a r y D e v { } ) ) } Run

No content

Concurrency f u n c m a i n ( ) { f o r i : = 0 ; i < 1 0 ; i + + { g o f m t . P r i n t l n ( i ) } / / S o m e t h i n g i s g o i n g t o g o w r o n g . . . } Run

... patterns f u n c d o i t ( i i n t , d o n e c h a n b o o l ) { t i m e . S l e e p ( t i m e . D u r a t i o n ( r a n d . I n t n ( 3 ) ) * t i m e . S e c o n d ) f m t . P r i n t l n ( i ) d o n e < - t r u e } f u n c m a i n ( ) { d o n e : = m a k e ( c h a n b o o l , 1 ) f o r i : = 0 ; i < 1 0 ; i + + { g o d o i t ( i , d o n e ) } f o r i : = 0 ; i < 1 0 ; i + + { s e l e c t { c a s e < - d o n e : c o n t i n u e c a s e < - t i m e . A f t e r ( t i m e . S e c o n d * 3 ) : l o g . P r i n t l n ( " T o o . . . m u c h . . . w a i t i n g . . . " ) r e t u r n } } } Run

No content

... and more patterns f u n c m a i n ( ) { v a r w g s y n c . W a i t G r o u p f o r i : = 0 ; i < 1 0 ; i + + { w g . A d d ( 1 ) g o f u n c ( i i n t ) { f m t . P r i n t l n ( i ) w g . D o n e ( ) } ( i ) } w g . W a i t ( ) } Run

OMG

Channels f u n c f i l l ( q u e u e c h a n < - P e r s o n , w g * s y n c . W a i t G r o u p ) { d e f e r c l o s e ( q u e u e ) d e f e r w g . D o n e ( ) f o r _ , n a m e : = r a n g e [ ] s t r i n g { " M i h a i " , " V i c t o r " , " F r a n c e s c " , " G e r m á n " , " A l e x " } { q u e u e < - P e r s o n { n a m e } t i m e . S l e e p ( t i m e . D u r a t i o n ( r a n d . I n t n ( 1 0 0 0 ) ) * t i m e . M i l l i s e c o n d ) } } f u n c v i s i t ( q u e u e < - c h a n P e r s o n , w g * s y n c . W a i t G r o u p ) { d e f e r w g . D o n e ( ) f o r p : = r a n g e q u e u e { f m t . P r i n t l n ( p . N a m e , " i s v i s i t i n g " ) } } f u n c m a i n ( ) { q u e u e : = m a k e ( c h a n P e r s o n , 2 ) / / . . . Run

Your own server v a r ( c o u n t e r i n t p o r t = 9 0 0 0 ) f u n c c o u n t ( w h t t p . R e s p o n s e W r i t e r , r * h t t p . R e q u e s t ) { c o u n t e r + + } f u n c s t a t s ( w h t t p . R e s p o n s e W r i t e r , r * h t t p . R e q u e s t ) { w . W r i t e ( [ ] b y t e ( f m t . S p r i n t f ( " V i s i t s : % d " , c o u n t e r ) ) ) } f u n c m a i n ( ) { / / h t t p . H a n d l e F u n c ( " / f a v i c o n . i c o " , f u n c ( _ h t t p . R e s p o n s e W r i t e r , _ * h t t p . R e q u e s t ) { } ) h t t p . H a n d l e F u n c ( " / " , c o u n t ) h t t p . H a n d l e F u n c ( " / s t a t s " , s t a t s ) l o g . P r i n t l n ( " L i s t e n i n g a t p o r t " , p o r t ) l o g . P a n i c ( h t t p . L i s t e n A n d S e r v e ( f m t . S p r i n t f ( " : % d " , p o r t ) , n i l ) ) } Run

Thank you Álex González agonzalezro@gmail.com (mailto:agonzalezro@gmail.com) http://agonzalezro.github.io (http://agonzalezro.github.io) @agonzalezro (http://twitter.com/agonzalezro)

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