Interpreter hangs while running a function

[pt7k]

1. Summary

   • Description: Bug Summary in 2 to 3 sentences.
   • While this specification provided to the interpreter is very similar to the example in issue Interpreter returns the unsat error for a function that runs fine and has a fp through rr #22 this time the program is hanging in an endless loop without any warnings or messages.
   • One can see the program continuously iterating by setting severity to debug.
   • It is also possible to get the same outcome as in the previously mentioned issue by shortening the specification to just o1[n] = g(o1[n-1]) that is by skipping the explicit assignment of 0 to the initial timeline.

2. Environment

   • Tau Version: for now "v0.7-alpha"
   • Build Number or Date: 90db47a
   • Operating System: Ubuntu

3. Steps to Reproduce
   Step 1: What input did you first provide?

sbf o1 = console
f(0) := {b}:sbf
f({a b}:sbf) := {a b}:sbf
g(x) := {a}:sbf f(x)
h[0]() := 0
h[n]() := g(h[n-1]())
n h()
# g(x) has a fixed point when being run through rr but hangs in a loop with the interpreter
r o1[0] = 0 && o1[n] = g(o1[n-1])

Step 2: Any additional input to Tau?

Expected Result
Same result from the interpreter as from the equivalent test through a recurrence relation h:

h[0]() = 0
h[1]() = { a b } : sbf
...

Actual Result
Program hanging

4. Additional Information
   • Error Messages or Logs:
   • Screenshots:

Partial debug output:

5. Severity and Impact

   • Severity Level: Minor
   • Impact on Work: Program Hanging

6. Workaround (if applicable)

   • Tell us if you found a way around this problem:
   • It's possible to prevent this particular example from going to an endless loop by not explicitly assigning 0 to o1[0] in the specification, but then the interpreter yields the unsat error:

7. Contact Information
   • Name: pt7k
   • Email: Telegram @ksdjfskfh
   • Additional Notes: Any other message for the Tau Team

Submission Instructions

• Make sure to attach any input files to this bug report.