showperms – an F# example

Console program to show permissions for all files and directories within given path hierarchies.

Usage looks like this:

Z% showperms nonexistentDir testDir
      Error: nonexistentDir – No such file or directory
drwxr-xr-x   testDir/
drwxr-xr-x   testDir/1d/
drwxr-xr-x   testDir/2d/
-rw-r--r--   testDir/2d/1f
drwxr-xr-x   testDir/2d/2d/
-rwxr-xr-x   testDir/2d/3f
----------   testDir/2d/4f
dr--------   testDir/3d/
             testDir/3d/1d
             testDir/3d/2f
d--------- ! testDir/4d/

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F# projects here:

• showperms – a simple CLI utility, exploiting F# features for maximum readabiilty
• showpermsOld – shorter, but more complicated and irregular code, less readability!
• DiffResults – for rendering test results as a diff

Jetbrains Rider IDE files included.

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showperms

Fully utilizing F# features

A shebang form is provided: showperms.fsx

Before testing, you must run createTestData.bash to create a testDir/ folder hierarchy.

In Rider, there is a Run Configuration that makes an executable for osx-arm64. It’s big, tho.

Depends on NuGet packages:

• Mono.Posix.NETStandard
• NaturalStringExtensions

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showpermsOld

Earlier version, not fully utilizing F# features. It’s shorter but more complicated, irregular, and harder to understand.

Depends on NuGet packages:

• Mono.Posix.NETStandard
• NaturalStringExtensions

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DiffResults library

Shows test failures all at once with a diff, instead of aborting at the first error.

Instead of an assert for each fact, where the test aborts at the first error, the test runs to completion and you see a diff of expected output printouts vs actual. Given these two files:

 expected                actual
 ––––––––                –––––– 
   yes                     no
   yes                     no
   what                    not
   where                   what
   why                     but
   when                    why          
   [newline after when]    [no newline after why]

Output looks like this:

x no
√ yes
x no
√ yes
x not
√ what
x what 
√ where
x but
  why
√ when
√ 

Key:
   x = wrong: found in expected; is not in actual
   √ = right: not found in expected; is in actual

Depends on NuGet package:

• DiffPlex