Reading gzip files in nimlang? - zip

Question

I've been trying to learn nimlang because it seems like it has a lot of potential to integrate with python simply - but I'm a windows guy. The script I'm trying to compile is a simple one:
import zip/gzipfiles # Import zip package
block:
let vcf = newGzFileStream("test.txt.gz") # Open gzip file
var line: string # Declare line variable
# Loop over each line in the file
while not vcf.atEnd():
line = vcf.readLine()
echo line
Using a test file that I've gzipped called 'test.txt.gz':
this
is
gzipped
It compiles successfully on windows linux subsystem, and regular linux:
bub#bubs-surface-book-2:/mnt/c/Users/bubth/Development/nim$ nim c read_gzip.nim
Hint: used config file '/etc/nim.cfg' [Conf]
Hint: system [Processing]
Hint: read_gzip [Processing]
Hint: gzipfiles [Processing]
Hint: os [Processing]
Hint: strutils [Processing]
Hint: parseutils [Processing]
Hint: math [Processing]
Hint: algorithm [Processing]
Hint: times [Processing]
Hint: posix [Processing]
Hint: ospaths [Processing]
Hint: zlib [Processing]
Hint: streams [Processing]
CC: read_gzip
Hint: [Link]
Hint: operation successful (22504 lines compiled; 0.634 sec total; 35.035MiB peakmem; Debug Build) [SuccessX]
bub#bubs-surface-book-2:/mnt/c/Users/bubth/Development/nim$ ./read_gzip
asdf
1234
test
this
works
bub#bubs-surface-book-2:/mnt/c/Users/bubth/Development/nim$
But on windows, it compiles but then doesn't know how to use the zlib dll:
PS C:\Users\bubth\Development\nim> nim c .\read_gzip.nim
Hint: used config file 'C:\Users\bubth\scoop\apps\nim\current\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: read_gzip [Processing]
Hint: gzipfiles [Processing]
Hint: os [Processing]
Hint: strutils [Processing]
Hint: parseutils [Processing]
Hint: math [Processing]
Hint: bitops [Processing]
Hint: macros [Processing]
Hint: algorithm [Processing]
Hint: unicode [Processing]
Hint: pathnorm [Processing]
Hint: osseps [Processing]
Hint: winlean [Processing]
Hint: dynlib [Processing]
Hint: times [Processing]
Hint: options [Processing]
Hint: typetraits [Processing]
Hint: time_t [Processing]
Hint: zlib [Processing]
Hint: streams [Processing]
Hint: [Link]
Hint: operation successful (37181 lines compiled; 0.921 sec total; 46.852MiB peakmem; Debug Build) [SuccessX]
PS C:\Users\bubth\Development\nim> .\read_gzip.exe
could not load: zlib1.dll
PS C:\Users\bubth\Development\nim>
I've tried installing zlib via https://github.com/microsoft/vcpkg but even after walking through and successfully "linking" things, it's not finding the libraries. I swear I'm not stupid, but what am I missing? Is there some special way to get those packages onto windows in a way that nimble will recognize?

Answer 1

It looks like zip package assumes that you have the dll installed if you're on windows, and doesn't include it. To fix this, I had to manually download the correct .dll file and add it to my path, after which it compiled and ran just fine.
PS C:\Users\bubth\Development\vcpkg> .\vcpkg.exe install zlib:x64-windows
Computing installation plan...
The following packages are already installed:
zlib[core]:x64-windows
Package zlib:x64-windows is already installed
Total elapsed time: 618.1 us
The package zlib is compatible with built-in CMake targets:
find_package(ZLIB REQUIRED)
target_link_libraries(main PRIVATE ZLIB::ZLIB)
PS C:\Users\bubth\Development\vcpkg>
Added the vcpkg bin folder to my Path environment variable
C:\Users\bubth\Development\vcpkg\installed\x64-windows\bin
Recompiled and it ran:
PS C:\Users\bubth\Development\nim> nim c --run .\read_gzip.nim
Hint: used config file 'C:\Users\bubth\scoop\apps\nim\current\config\nim.cfg' [Conf]
Hint: system [Processing]
Hint: widestrs [Processing]
Hint: io [Processing]
Hint: read_gzip [Processing]
Hint: gzipfiles [Processing]
Hint: os [Processing]
Hint: strutils [Processing]
Hint: parseutils [Processing]
Hint: math [Processing]
Hint: bitops [Processing]
Hint: macros [Processing]
Hint: algorithm [Processing]
Hint: unicode [Processing]
Hint: pathnorm [Processing]
Hint: osseps [Processing]
Hint: winlean [Processing]
Hint: dynlib [Processing]
Hint: times [Processing]
Hint: options [Processing]
Hint: typetraits [Processing]
Hint: time_t [Processing]
Hint: zlib [Processing]
Hint: streams [Processing]
Hint: [Link]
Hint: operation successful (37182 lines compiled; 1.361 sec total; 58.07MiB peakmem; Debug Build) [SuccessX]
Hint: C:\Users\bubth\Development\nim\read_gzip.exe [Exec]
asdf
1234
test
this
works
PS C:\Users\bubth\Development\nim>

Answer 2

The source code for the zip nimble package, which I presume you are using, seems to be a wrapper around the zlib found at https://www.zlib.net. From there you have a few windows links which might contain the .dll file you need, particularly promising looks the zlib for windows website.
If you keep having problems with this module you could try creating an issue at the GitHub project, that README could really have a few links to binary downloads of the .dll you need.