New answers tagged evaluation
3
We can (ab)use the automatic expansion of OptionValue into its three-argument-form, which works even inside rules:
Options[func] = {"opt" -> None};
{func["opt" -> 1], func[]} /. func[OptionsPattern[]] :> OptionValue["opt"]
(* {1, None} *)
Now, for your example: First, we define iExpandOptionValue that takes expands ...
5
It's pretty simple: you just make sure that the function pattern never matches illegal arguments. For example:
ClearAll[f]
f[a_ /; a != 0] := 1;
f[0]
f[2]
f[0]
1
Sometimes you also want to do something (like issue a message) before returning the expression unevaluated. You can do this by adding to following definition to f (don't clear the previous ...
1
I'd use Mr.Wizard's step[] function for the most generality.
(* https://mathematica.stackexchange.com/a/1447 *)
step // ClearAll;
SetAttributes[step, HoldAll]
step[expr_] := Module[{P}, P = (P = Return[#, TraceScan] &) &;
TraceScan[P, expr, TraceDepth -> 1]];
setParameters // ClearAll;
SetAttributes[setParameters, HoldAll];
setParameters[...
2
Here is another implementation of joebolte's TraceView using the new Tree functionality in 12.3:
SetAttributes[TraceView, HoldFirst];
TraceView[expr_] := Module[{trace, f, h, tree},
trace = Trace[expr, TraceOriginal -> True];
f[steps_List] := Rest[steps];
f[step_] := {};
h[steps_List] := First[steps];
h[step_] := step;
tree = NestTree[f, trace,...
4
The current status of this answer
I intend to return back to this very exciting question with a better answer, when I have it, but for now there will be something here to get you started.
General aspects of WL DSL creation
The main steps in creating a WL DSL
There are a few steps in WL DSL creation which seem to be universal and applicable to most cases:
...
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