Thank you. I did not get it, but it is already discussed above. :( :)

We will be sharing the link to the quiz during the Study Group session and will also include the link in the reminder emails for the live sessions as well as the recordings.

I found it necessary to answer all the questions before grading.

If a function f depends on functions gi containing certain restrictions on their arguments, e.g. g1[x,yInteger] (for technical reasons I could not insert the underscore). How to modify f, so that it will inherit the restrictions from all g without putting them explicitly (and manually) in f's definition? Thanks.

Hi Rohit, I can confirm autograder is accepting the right answer for #8.

Thanks for your thoughtfulness about sharing answers. I'll take a look.

You can retrieve cloud code with CloudGet or CloudImport:

obj = CloudPut[Hold[f[x_] := x^2;], IncludeDefinitions -> True];
ClearAll[f];
ReleaseHold[CloudGet[obj]];
f[3]

(I included the ClearAll[f] to be absolutely sure that the definition for f was being pulled from the cloud and not locally.) If you then wanted to save the definition of f locally, you could save the output of Definition[f] to a file.

Also, you can download the source code of a resource function by clicking the 'Source Notebook' button. And while resource functions are not "official" Wolfram Language functions, many are provided by Wolfram staff and are quite robust.

Hi John,

Looking at your attached notebook: if you don't know what variables are going to be in expr, then localising with Block seems fine to me.

That said... if you're localising particular variables (say, x and y), that suggests to me that you do know what variables are going to be in expr...? If that's the case, I would define it as expr[x_, y_] := Plus[x, y]. Then, if you define f as f[x_, y_] := expr[x, y], you can do without the Block.

In other words:

ClearAll[f1, f2, expr1, expr2, x, y];
x = 1; y = 2;

(* What you're doing now: *)
expr1 := Plus[x, y];
Block[{x, y}, f1[x_, y_] := Evaluate[expr1]]
f1[3, 4]

(* What I would do instead, if possible: *)
expr2[x_, y_] := Plus[x, y];
f2[x_, y_] := expr2[x, y];
f2[3, 4]

Side note: have you used \[FormalX] and \[FormalY] before? They can be handy for avoiding conflicts with global variables.

I'd like some help to understand the statements in Wednesday's lesson, which I'll copy here and hope you can identify back to the lesson workbook.

(* When no explicit RoundingRadius is given, scale it with the \
FrameMargin: *)
frameText[text_String, options : OptionsPattern[]] /; 
   FreeQ[{options}, RoundingRadius] := Framed[
   Text[text],
   RoundingRadius -> OptionValue[FrameMargins]/2,
   Sequence @@ 
    DeleteCases[{options}, Alternatives[RoundingRadius -> _]]
   ];

I don't understand how to inquire on the value of text and options when the function call is parsed ie. frameText[text_String, options : OptionsPattern[]] . Perhaps first question is whether once can inquire what would be assigned to text and to options?

In any case the programmer placed option is a List ie {options} inside function calls to FreeQ and DeleteCases. They also knew it was sufficient to ask test {options} with RoundingRadius instead of "RoundingRadius" in FreeQ. which isn't entirely obvious from the Help Documentation of FreeQ.

I'm also not entirely sure how to interpret Alternatives[RoundingRadius -> _ used inside the call to DeleteCases. The documentation of Alternatives describes usage with more than one alternative to choose from so Alternative[arg] is vague. Lastly my understanding of the syntax RoundingRadius->_ would require that RoundingRadius->val was assigned which FreeQ would have screen out as False so would this whole statement not be redundant and so never called upon?

Thanks.

Thank you Daniel, that helped me understand how to determine what is assigned to options. No need to worry about what I meant by parsing, you provided all the information I needed. John

Some additional resources (Especially for beginners in the Wolfram Language):

• Defining Your Own Functions -- a video lesson from the interactive course An Elementary Introduction to the Wolfram Langauge (Please sign in with your Wolfram ID to access free interactive courses on Wolfram U)
• Function Definitions -- a chapter from the online tutorial The Wolfram Language: Fast Introduction for Programmers