Building a package locally from source using "stack"
Discussion

Building a package locally from source using "stack"

Use case

One wants to use the original sources of a package (of the Stackage/Hackage repository), to modify it's files locally, and in order to investigate or contribute to improvement.

Procedures

We can choose out of the following two opportunities:

without use of tarball files
with use of tarball files

Procedure without tarball files

unpack the package that should be obtained as source code

command:
```
stack unpack random
```
or command with dedicated version number:
```
stack unpack random-1.2.1
```

output:

Unpacked random (from Hackage) to C:\Qsync\SwEng\GitHub\JB\SandBox\Test7\random-1.2.1\

change the current directory
- command:
```
cd random-1.2.1
```

initialise the folder of the package (here `random-1.2.1`), will create file `stack.yaml`

command:
```
stack init
```

output:

Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- .\

Selecting the best among 20 snapshots...

* Matches https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml

Selected resolver: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml
Initialising configuration using resolver: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml
Total number of user packages considered: 1
Writing configuration to file: stack.yaml
All done.

change the current directory back to the main one
- command:
```
cd ..
```

to `stack.yaml` of main project, add package with relative path (here `./random-1.2.1`) to section `packages` !!!

extract

#   - auto-update
#   - wai
packages:
- .
- ./random-1.2.1

# Dependency packages to be pulled from upstream that are not in the resolver.
# These entries can reference officially published versions as well as

to `package.yaml` of main project add dependency to package (here `random`) with constraint (here ` == 1.2.1`) to section `dependencies`

extract

.
.
.
# common to point users to the README.md file.
description:         Please see the README on GitHub at <https://github.com/githubuser/Test7#readme>

dependencies:
- base >= 4.7 && < 5
- random == 1.2.1

library:
  source-dirs: src
.
.
.

delete cabal-file (here `Test7.cabal`), if any

build the main project

command:
```
stack build
```

output:

random> configure (lib)
random> Configuring random-1.2.1...
random> build (lib)
random> Preprocessing library for random-1.2.1..
random> Building library for random-1.2.1..
random> copy/register
random> Installing library in C:\Qsync\SwEng\GitHub\JB\SandBox\Test7\.stack-work\install\f1fb6c00\lib\x86_64-windows-ghc-8.10.7\random-1.2.1-HT6KBuAXK636deJWA2IfmN
random> Registering library for random-1.2.1..
Building all executables for `Test7' once. After a successful build of all of them, only specified executables will be rebuilt.
Test7 > configure (lib + exe)
Test7 > Configuring Test7-0.1.0.0...
Test7 > build (lib + exe)
Test7 > Preprocessing library for Test7-0.1.0.0..
Test7 > Building library for Test7-0.1.0.0..
Test7 > [1 of 2] Compiling Lib
Test7 > [2 of 2] Compiling Paths_Test7
Test7 > Preprocessing executable 'Test7-exe' for Test7-0.1.0.0..
Test7 > Building executable 'Test7-exe' for Test7-0.1.0.0..
Test7 > [1 of 2] Compiling Main
Test7 > [2 of 2] Compiling Paths_Test7
Test7 > Linking .stack-work\dist\274b403a\build\Test7-exe\Test7-exe.exe ...
Test7 > copy/register
Test7 > Installing library in C:\Qsync\SwEng\GitHub\JB\SandBox\Test7\.stack-work\install\f1fb6c00\lib\x86_64-windows-ghc-8.10.7\Test7-0.1.0.0-7rSbgHQwCYG6qywGwlMXqh
Test7 > Installing executable Test7-exe in C:\Qsync\SwEng\GitHub\JB\SandBox\Test7\.stack-work\install\f1fb6c00\bin
Test7 > Registering library for Test7-0.1.0.0..
Completed 2 action(s).

Procedure with tarball files

unpack the package that should be obtained as source code

command:
```
stack unpack random
```
or command with dedicated version number:
```
stack unpack random-1.2.1
```

output:

Unpacked random (from Hackage) to C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\random-1.2.1\

change the current directory
- command:
```
cd random-1.2.1
```

initialise the folder of the package (here `random-1.2.1`), will create file `stack.yaml`

command:
```
stack init
```

output:

Looking for .cabal or package.yaml files to use to init the project.
Using cabal packages:
- .\

Selecting the best among 20 snapshots...

* Matches https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml

Selected resolver: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml
Initialising configuration using resolver: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/18/25.yaml
Total number of user packages considered: 1
Writing configuration to file: stack.yaml
All done.

generate a tarball file of the package code

command:
```
stack sdist
```

output:

Getting file list for C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\random-1.2.1\
random> List of package sources written to file
random> 'C:\Users\Joerg\AppData\Local\Temp\stack-sdist-fede07f57c5e6536\source-files-list'
Building sdist tarball for C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\random-1.2.1\
Wrote sdist tarball to C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\random-1.2.1\.stack-work\dist\274b403a\random-1.2.1.tar.gz
Checking package 'random' for common mistakes
Package check reported the following warnings:
'ghc-options: -O2' is rarely needed. Check that it is giving a real benefit and not just imposing longer compile times on your users.

change the current directory back to the main one
- command:
```
cd ..
```

to `stack.yaml` of main project, add package with relative path (here `./random-1.2.1`) to section `extra-deps`

extract

.
.
.
# extra-deps:
# - acme-missiles-0.3
# - git: https://github.com/commercialhaskell/stack.git
#   commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
#
# extra-deps: []
extra-deps:
- ./random-1.2.1

# Override default flag values for local packages and extra-deps
# flags: {}
.
.
.

to `package.yaml` of main project add dependency to package (here `random`) with constraint (here ` == 1.2.1`) to section `dependencies`

extract

.
.
.
# common to point users to the README.md file.
description:         Please see the README on GitHub at <https://github.com/githubuser/Test6#readme>

dependencies:
- base >= 4.7 && < 5
- random == 1.2.1

library:
  source-dirs: src
.
.
.

delete cabal-file (here `Test6.cabal`), if any

build the main project

command:
```
stack build
```

output:

random> configure (lib)
random> Configuring random-1.2.1...
random> build (lib)
random> Preprocessing library for random-1.2.1..
random> Building library for random-1.2.1..     
random> [1 of 4] Compiling System.Random.GFinite
random> [2 of 4] Compiling System.Random.Internal
random> [3 of 4] Compiling System.Random
random> [4 of 4] Compiling System.Random.Stateful
random> copy/register
random> Installing library in C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\.stack-work\install\f1fb6c00\lib\x86_64-windows-ghc-8.10.7\random-1.2.1-HT6KBuAXK636deJWA2IfmN
random> Registering library for random-1.2.1..
Building all executables for `Test6' once. After a successful build of all of them, only specified executables will be rebuilt.
Test6 > configure (lib + exe)
Configuring Test6-0.1.0.0...
Test6 > build (lib + exe)
Preprocessing library for Test6-0.1.0.0..
Building library for Test6-0.1.0.0..
[1 of 2] Compiling Lib
[2 of 2] Compiling Paths_Test6
Preprocessing executable 'Test6-exe' for Test6-0.1.0.0..
Building executable 'Test6-exe' for Test6-0.1.0.0..
[1 of 2] Compiling Main
[2 of 2] Compiling Paths_Test6
Linking .stack-work\dist\274b403a\build\Test6-exe\Test6-exe.exe ...
Test6 > copy/register
Installing library in C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\.stack-work\install\f1fb6c00\lib\x86_64-windows-ghc-8.10.7\Test6-0.1.0.0-37H5nARYQZNVVlIIsBxXW
Installing executable Test6-exe in C:\Qsync\SwEng\GitHub\JB\SandBox\Test6\.stack-work\install\f1fb6c00\bin
Registering library for Test6-0.1.0.0..
Completed 2 action(s).

Table of Contents

Building a package locally from source using "stack"

Use case

Procedures

Procedure without tarball files

Procedure with tarball files

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