How to enable "Tracing" in Isabelle/jEdit - isabelle

Question

I'm a vim fan, but only emacs has this Isabelle/HOL environment. jEdit is great, but I cannot use
using [[simp_trace=true]]
like in emacs.
How to enable "Tracing" in jEdit?

Answer 1

You can indeed use simp_trace in the middle of a proof in Isabelle/jEdit, like so:
lemma "(2 :: nat) + 2 = 4"
using [[simp_trace]]
apply simp
done
Alternatively, you can declare it globally, like so:
declare [[simp_trace]]
lemma "(2 :: nat) + 2 = 4"
apply simp
done
Both give you the simplifier's trace in the "Output" window when your cursor is just after the apply simp statement in jEdit.

Answer 2

If you need a trace depth deeper than 1 (default), you fine-tune it by
declare [[simp_trace_depth_limit=4]]
This example then gives a trace depth of 4.

Answer 3

As others have pointed out, you can use simp_trace. However, you can also use simp_trace_new combined with the "Simplifier Trace" window. This provides improved output over simp_trace:
lemma "rev (rev xs) = xs"
using [[simp_trace_new]]
apply(induction xs)
apply(auto)
done
To view the trace, position the cursor over "apply(auto)" then click on "See simplifier trace". The "Simplifier Trace" window(tab) should open. Click on "Show Trace" and a new window should appear showing a trace for each subgoal.
The Isabelle/Isar reference provides more details:
simp_trace_new controls Simplifier tracing within Isabelle/PIDE applications, notably Isabelle/jEdit.
This provides a hierarchical representation of the rewriting steps performed by the Simplifier.
Users can configure the behaviour by specifying breakpoints, verbosity
and enabling or disabling the interactive mode.
In normal verbosity (the default), only rule applications matching a breakpoint will be
shown to the user. In full verbosity, all rule applications will be logged.
Interactive mode interrupts the normal flow of the Simplifier and defers
the decision how to continue to the user via some GUI dialog.
Alternatively you can specify "using [[simp_trace_new mode=full]]" link here
To see all steps taken by the simplifier.
NOTE: in the previous example, showing the trace of "apply(induction xs)" yields no output.