How to find all package we can Needs

Question

We can encounter that interesting package sometimes,like GUIKit`,but I don't know how to find those.I can found that package which has been default loaded

Union[Select[GeneralUtilities`SymbolNameContext /@ 
   GeneralUtilities`ExtendedNames[All], StringCount[#, "`"] == 1 &]]

{Algebra`,AlphaIntegration`,Assumptions`,AssumptionsDump`,Audio`,AugmentedData`,BinningUtilities`,BoxForm`,BoxFormat`,BrowserCategoryLoad`,Calendar`,CCodeGenerator`,CCompilerDriver`,Charting`,Clipboard`,CloudObject`,CloudSystem`,Compile`,Compiler`,ComplexAnalysis`,Conditional`,ConsoleWindow`,Control`,ControlSystems`,Conversion`,CUDAInformation`,Data`,Database`,DatabaseLink`,DataPaclets`,Dataset`,DateAndTime`,Debug`,Debugger`,Deconvolve`,Developer`,...}

But It's don't include GUIKit`.So how to find those package which have not been default loaded but exist in my local disk?

You can find source code of many packages if you evaluate SystemOpen@FileNameJoin[{$InstallationDirectory, "AddOns"}] . In the subfolder "Packages" there is also GUIKit package. — Pinti, Mar 13 '17 at 13:53
@Pinti Oh,I find that,so this folder contain all package we can Needs? — yode, Mar 13 '17 at 13:56
I think Needs looks for packages in all folders listed in $Path. — Pinti, Mar 13 '17 at 14:06
@Pinti Thanks for your explanation,I thinks if you compose it for read,I will accepted that. — yode, Mar 13 '17 at 14:07

score 4 · Accepted Answer · answered Mar 13 '17 at 14:15

Needs by default searches for packages in folders listed in $Path.

One of the elements of $Path is also FileNameJoin[{$InstallationDirectory, "AddOns"}] where you can find source code of many additional packages that come with Mathematica but are not part of System context.

How to find all package we can Needs

1 Answers1