Skip to main content

Check if symbol is in core language


How can I check if a symbol is pre-defined by Mathematica, in a way that's backwards compatible with old versions?


i.e. I would like some CoreLanguageQ[x_Symbol] which matches CoreLangaugeQ[Print], but not CoreLanguageQ[f]



Then it can be used to help make code backwards compatible, eg.


If[!CoreLanguageQ[Echo], Echo[x_]:= (Print[x];x)]

Thank you.



Answer



You can look it up using WolframLanguageData, which has a list of all pre-defined symbols:


ClearAll[CoreLanguageQ]
SetAttributes[CoreLanguageQ, HoldAll]
CoreLanguageQ[x_] := With[{name = SymbolName[x]}, CoreLanguageQ[name]]
CoreLanguageQ[x_String] := With[{

   names = WolframLanguageData[All, "Name"]
   }, MemberQ[names, x]]

CoreLanguageQ[Plot]
(* Out: True *)

CoreLanguageQ[Plott]
(* Out: False *)

Looking at the context of the symbol is also a viable approach. However, the WolframLanguageData approach is appealing because the documentation states that




WolframLanguageData[] gives a list of all Wolfram Language symbols.



Which is to say, the list returned by this function is by definition Wolfram Language. This is as close as a definition of "core language" that we can come.


For the problem in the updated question, it would seem appropriate to check if a symbol exists in the System context like QuantumDot suggests in a comment.


The only backward compatible way to use this would be to create lists of functions available for specific versions and include them in your code. For example:


names = WolframLanguageData[All, "Name"];
versionIntroduced = WolframLanguageData[All, "VersionIntroduced"];
allowed = Pick[names, Thread[versionIntroduced <= 10]];


In this code, allowed holds all the symbols that exist in version 10, presuming that no symbol previously introduced was removed.


Comments

Post a Comment

Popular posts from this blog

functions - Get leading series expansion term?

Given a function f[x] , I would like to have a function leadingSeries that returns just the leading term in the series around x=0 . For example: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x)] x and leadingSeries[(1/x + 2 + (1 - 1/x^3)/4)/(4 + x)] -(1/(16 x^3)) Is there such a function in Mathematica? Or maybe one can implement it efficiently? EDIT I finally went with the following implementation, based on Carl Woll 's answer: lds[ex_,x_]:=( (ex/.x->(x+O[x]^2))/.SeriesData[U_,Z_,L_List,Mi_,Ma_,De_]:>SeriesData[U,Z,{L[[1]]},Mi,Mi+1,De]//Quiet//Normal) The advantage is, that this one also properly works with functions whose leading term is a constant: lds[Exp[x],x] 1 Answer Update 1 Updated to eliminate SeriesData and to not return additional terms Perhaps you could use: leadingSeries[expr_, x_] := Normal[expr /. x->(x+O[x]^2) /. a_List :> Take[a, 1]] Then for your examples: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x), x] leadingSeries[Exp[x], x] leadingSeries[(1/x + 2 + (1 - 1/x...
Post a Comment
Read more

How to thread a list

I have data in format data = {{a1, a2}, {b1, b2}, {c1, c2}, {d1, d2}} Tableform: I want to thread it to : tdata = {{{a1, b1}, {a2, b2}}, {{a1, c1}, {a2, c2}}, {{a1, d1}, {a2, d2}}} Tableform: And I would like to do better then pseudofunction[n_] := Transpose[{data2[[1]], data2[[n]]}]; SetAttributes[pseudofunction, Listable]; Range[2, 4] // pseudofunction Here is my benchmark data, where data3 is normal sample of real data. data3 = Drop[ExcelWorkBook[[Column1 ;; Column4]], None, 1]; data2 = {a #, b #, c #, d #} & /@ Range[1, 10^5]; data = RandomReal[{0, 1}, {10^6, 4}]; Here is my benchmark code kptnw[list_] := Transpose[{Table[First@#, {Length@# - 1}], Rest@#}, {3, 1, 2}] &@list kptnw2[list_] := Transpose[{ConstantArray[First@#, Length@# - 1], Rest@#}, {3, 1, 2}] &@list OleksandrR[list_] := Flatten[Outer[List, List@First[list], Rest[list], 1], {{2}, {1, 4}}] paradox2[list_] := Partition[Riffle[list[[1]], #], 2] & /@ Drop[list, 1] RM[list_] := FoldList[Transpose[{First@li...
Post a Comment
Read more

front end - keyboard shortcut to invoke Insert new matrix

I frequently need to type in some matrices, and the menu command Insert > Table/Matrix > New... allows matrices with lines drawn between columns and rows, which is very helpful. I would like to make a keyboard shortcut for it, but cannot find the relevant frontend token command (4209405) for it. Since the FullForm[] and InputForm[] of matrices with lines drawn between rows and columns is the same as those without lines, it's hard to do this via 3rd party system-wide text expanders (e.g. autohotkey or atext on mac). How does one assign a keyboard shortcut for the menu item Insert > Table/Matrix > New... , preferably using only mathematica? Thanks! Answer In the MenuSetup.tr (for linux located in the $InstallationDirectory/SystemFiles/FrontEnd/TextResources/X/ directory), I changed the line MenuItem["&New...", "CreateGridBoxDialog"] to read MenuItem["&New...", "CreateGridBoxDialog", MenuKey["m", Modifiers-...
Post a Comment
Read more