[go-nuts] lazy evaluation and immuntability in golang

On Tue, Apr 29, 2014 at 12:31 PM, will wrote:
Does golang support the following:

Lazy evaluation (define a variable, load it in memory and only use it when
needed)

On 29 April 2014 11:31, will wrote:
Does golang support the following:

- Lazy evaluation (define a variable, load it in memory and only use
it when needed)

On Tuesday, 29 April 2014 12:45:55 UTC+2, chris dollin wrote:
Yes and no. It depends on how much work your're prepared to do before
one stops saying it's "supported".

It's not there as an automatic pervasive property of the language
(unlike Haskell). Mixing lazy evaluation with an avowedly imperative
language is likely to be ... complicated.

- immutability (i.e creating a variable that is immutable) e.g. int,
double, long?


Yes and no. It depends on how much work your're prepared to do before
one stops saying it's "supported".

To make a variable immutable, (a) make it unexported, and (b) don't
assign to it in its declaring package.

Or don't use a variable; use a const, for those types and initialising
expressions that permit it.

Are you trying to solve a programming problem or just characterise
the language?

Chris

--
Chris "allusive" Dollin

On 29/04/2014 9:03 pm, "will" wrote:
At this stage its looking at the characteristic of the language (looking

On Tuesday, 29 April 2014 13:06:48 UTC+2, Jesse McNelis wrote:

at the equivalent how certain things can be done in go which are done say
in scala or haskell)
Haskell and Scala are very different languages to Go. Comparing them on a
feature by feature basis won't be useful.

On Tuesday, April 29, 2014 5:31:07 PM UTC+7, will wrote:


Does golang support the following:

- Lazy evaluation (define a variable, load it in memory and only use
it when needed)
- immutability (i.e creating a variable that is immutable) e.g. int,
double, long?


regards,

Will

On Tuesday, 29 April 2014 13:05:49 UTC+1, Hai Thanh Nguyen wrote:
Go simply sucks when talking about features, the beauty of Go comes from
simplitcity.

On Tuesday, April 29, 2014 4:31:07 AM UTC-6, will wrote:
Does golang support the following:

- Lazy evaluation (define a variable, load it in memory and only use
it when needed)

I once tried to write a lazy-evaluation package in Go based on channels.

On Thursday, 1 May 2014 20:43:34 UTC+1, Scott Pakin wrote:
The basic idea was to use goroutines and channels to represent lazy
computations. A lazy function would first write a probe message into an
unbuffered channel, then perform its computation, and finally write the
result into a (typically different) channel. Consequently, the function
would block until a consumer requested its value by reading from the
unbuffered channel.

This split-phase operation was a bit clunky to abstract into a
general-purpose package so I gave up working on it. Still, it does
indicate that lazy evaluation can be implemented in Go—not as pervasively
as in Haskell but not much worse than Scheme's delay and force primitives.

— Scott