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Today's Topics:
1. Re: The (x:xs) in function parameter is a tuple? (Rein Henrichs)
2. Re: The (x:xs) in function parameter is a tuple? (Graham Gill)
3. Stack minimal dependency specification, or dependency tree
output (Lyndon Maydwell)
4. Re: Stack minimal dependency specification, or dependency
tree output (Mark Fine)
5. Re: Stack minimal dependency specification, or dependency
tree output (Lyndon Maydwell)
----------------------------------------------------------------------
Message: 1
Date: Wed, 24 Feb 2016 18:24:06 +0000
From: Rein Henrichs <rein.henri...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] The (x:xs) in function parameter is a
tuple?
Message-ID:
<cajp6g8zjstny94mfhpwa81w3w4wgcs7r9csy+7pueqkf7v3...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
A tuple can have any number of elements. (1,2) is a 2-tuple. (1,2,3) is a
3-tuple. (x:xs) and (x,y) are differently typed: xs must be a list of the
type of x, while y can be any type. (x:xs) is not a tuple. It is a list by
definition.
On Wed, Feb 24, 2016 at 2:45 AM Imants Cekusins <ima...@gmail.com> wrote:
> Hello Xiao,
>
> (one_element) -- is evaluation
> (element,element,...) -- is tuple
>
> (1:[2]) -- [1,2] because it is one "array element"
> (1,2) -- is a tuple because there are 2 elements
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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Message: 2
Date: Wed, 24 Feb 2016 13:37:08 -0500
From: Graham Gill <math.simp...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] The (x:xs) in function parameter is a
tuple?
Message-ID: <56cdf854.7070...@gmail.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
Hi Nan, are you just confused about the use of the parentheses "(" and ")"?
(x1,x2), (x1,x2,x3), ... are tuples in Haskell, but (x:xs) is not.
(There's no "one-ple", or 1-tuple, in Haskell.) In
occurs value [] = 0
occurs value (x:xs) = (if value == x then 1 else 0) + occurs value xs
the "(" and ")" around "x:xs" are just there for grouping, for operator
precedence reasons. Function application binds more tightly than ":". If
you leave the parentheses off, such as in
occurs value x:xs = ...
you'll get a parse error.
Graham
On 2/24/2016 5:31 AM, Nan Xiao wrote:
> Hi all,
>
> Greetings from me!
>
> I am confused about the function parameters and tuple. E.g.:
>
> occurs value [] = 0
> occurs value (x:xs) = (if value == x then 1 else 0) + occurs value xs
>
> should we consider (x:xs) as a tuple?
>
> Thanks in advance!
>
> Best Regards
> Nan Xiao
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
------------------------------
Message: 3
Date: Thu, 25 Feb 2016 08:07:04 +1100
From: Lyndon Maydwell <maydw...@gmail.com>
To: Biginners Haskell Mailinglist <beginners@haskell.org>
Subject: [Haskell-beginners] Stack minimal dependency specification,
or dependency tree output
Message-ID:
<CAM5QZtwa-T2iG=M33pYaMZASs=T3FCYx8X_7j8nzfM5tSSH=4...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Beginners,
I'm finally getting my hands dirty with Stack, and am using it in
conjunction with Docker, but not with the built-in docker functionality.
My Dockerfile is constructed so that it first installs a whole bunch of
dependencies globally, like so:
...
RUN stack install HUnit
...
Then after that, installs the project:
...
COPY . /app
WORKDIR /app
RUN stack install
...
This means that on repeated docker builds the app build and install time
should be limited to just the application itself, because the dependency
builds were cached. Which is great! However, I'm currently generating the
list of dependencies just by looking at the output of the stack build of
the app, and this displays everything as a flat list.
I'd like to see some kind of tree instead, so that when I pre-install the
dependencies, I can specify a minimal list, rather than a whole slew of
dependencies that would be pulled in transitively anyway.
Is there an easy way to do this?
Regards,
- Lyndon
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Message: 4
Date: Wed, 24 Feb 2016 14:04:19 -0800
From: Mark Fine <mark.f...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] Stack minimal dependency
specification, or dependency tree output
Message-ID:
<canrz_fkcb-p+ib-g4ophssyktldp62un7z_5t0zqxdpncn5...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
You can ask stack to build only dependencies and use that as a cache layer
for docker. We do something like:
FROM haskell:7.10
WORKDIR /app
COPY LICENSE Setup.hs simple-app.cabal stack.yaml /app/
RUN stack setup
RUN stack build simple-app --only-dependencies
COPY main /app/main
COPY src /app/src
RUN stack build simple-app --copy-bins
On Wed, Feb 24, 2016 at 1:07 PM, Lyndon Maydwell <maydw...@gmail.com> wrote:
> Hi Beginners,
>
>
> I'm finally getting my hands dirty with Stack, and am using it in
> conjunction with Docker, but not with the built-in docker functionality.
>
> My Dockerfile is constructed so that it first installs a whole bunch of
> dependencies globally, like so:
>
> ...
> RUN stack install HUnit
> ...
>
> Then after that, installs the project:
>
> ...
> COPY . /app
> WORKDIR /app
> RUN stack install
> ...
>
> This means that on repeated docker builds the app build and install time
> should be limited to just the application itself, because the dependency
> builds were cached. Which is great! However, I'm currently generating the
> list of dependencies just by looking at the output of the stack build of
> the app, and this displays everything as a flat list.
>
> I'd like to see some kind of tree instead, so that when I pre-install the
> dependencies, I can specify a minimal list, rather than a whole slew of
> dependencies that would be pulled in transitively anyway.
>
> Is there an easy way to do this?
>
>
> Regards,
>
> - Lyndon
>
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
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Message: 5
Date: Thu, 25 Feb 2016 09:10:30 +1100
From: Lyndon Maydwell <maydw...@gmail.com>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <beginners@haskell.org>
Subject: Re: [Haskell-beginners] Stack minimal dependency
specification, or dependency tree output
Message-ID:
<CAM5QZtyvGbo9y3=avf8halw1z0cxaoonq4oratygsfionkj...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hi Mark,
That would be great, and I have tried that, but there is one issue that
caused me to take the current approach instead.
The issue is that every change to
* Setup.hs
* simple-app.cabal
* stack.yaml
will cause the docker to consider the copy statement
> COPY LICENSE Setup.hs simple-app.cabal stack.yaml /app/
as a fresh checkpoint, and make the cache unusable. Since I've frequently
changing stack.yaml, and app.cabal, this won't help me much.
Not sure if there's a way around that with this method.
Let me know if I've overlooked something with your approach!
- Lyndon
On Thu, Feb 25, 2016 at 9:04 AM, Mark Fine <mark.f...@gmail.com> wrote:
> You can ask stack to build only dependencies and use that as a cache layer
> for docker. We do something like:
>
> FROM haskell:7.10
>
> WORKDIR /app
>
> COPY LICENSE Setup.hs simple-app.cabal stack.yaml /app/
> RUN stack setup
> RUN stack build simple-app --only-dependencies
>
> COPY main /app/main
> COPY src /app/src
> RUN stack build simple-app --copy-bins
>
>
> On Wed, Feb 24, 2016 at 1:07 PM, Lyndon Maydwell <maydw...@gmail.com>
> wrote:
>
>> Hi Beginners,
>>
>>
>> I'm finally getting my hands dirty with Stack, and am using it in
>> conjunction with Docker, but not with the built-in docker functionality.
>>
>> My Dockerfile is constructed so that it first installs a whole bunch of
>> dependencies globally, like so:
>>
>> ...
>> RUN stack install HUnit
>> ...
>>
>> Then after that, installs the project:
>>
>> ...
>> COPY . /app
>> WORKDIR /app
>> RUN stack install
>> ...
>>
>> This means that on repeated docker builds the app build and install time
>> should be limited to just the application itself, because the dependency
>> builds were cached. Which is great! However, I'm currently generating the
>> list of dependencies just by looking at the output of the stack build of
>> the app, and this displays everything as a flat list.
>>
>> I'd like to see some kind of tree instead, so that when I pre-install the
>> dependencies, I can specify a minimal list, rather than a whole slew of
>> dependencies that would be pulled in transitively anyway.
>>
>> Is there an easy way to do this?
>>
>>
>> Regards,
>>
>> - Lyndon
>>
>>
>> _______________________________________________
>> Beginners mailing list
>> Beginners@haskell.org
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>>
>>
>
> _______________________________________________
> Beginners mailing list
> Beginners@haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
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