Tons of more debug capabilities.(0.26.0)

examples/debug_reporting.fun

@@ -0,0 +1,93 @@
+//!/usr/bin/env fun
+
+/*
+ * Debugging and error reporting demo for Fun.
+ *
+ * How to run:
+ *   fun --repl-on-error examples/debug_reporting.fun
+ *
+ * What happens:
+ *   - The program runs compute(), then triggers a runtime error in crash().
+ *   - The VM drops you into the REPL at the error site with the stack preserved.
+ *
+ * Try these REPL commands when it stops:
+ *   :backtrace           # or :bt — show frames (most recent first)
+ *   :locals              # locals in the current (top) frame
+ *   :stack               # show the value stack
+ *   :top                 # show the top-of-stack value
+ *   :list                # show source around the current line
+ *   :disas               # disassemble around current instruction pointer (ip)
+ *   :frame 1             # select a lower frame, then try :locals, :list, :disas again
+ *   :printv local[0]     # print a single value (also: stack[i], global[i])
+ *
+ * Stepping and breakpoints:
+ *   - Before re-running the script, you can set a breakpoint at the marker below.
+ *     For example (adjust the line number as needed in your copy):
+ *       :break examples/debug_reporting.fun:LINE_BK_1
+ *       :info breaks
+ *       :cont
+ *     On hit, try stepping:
+ *       :step            # step one instruction
+ *       :next            # step over
+ *       :finish          # run until current frame returns
+ *       :cont            # continue until next stop (breakpoint or error)
+ *
+ * Note: If line numbers drift due to edits, use :list and :backtrace to locate the desired spot,
+ * then set the breakpoint with the correct file:line.
+ */
+
+/* A small helper computation to set a breakpoint on */
+fun add(a, b)
+  // Simple arithmetic to have a few instructions to step over
+  c = a + b
+  print(c)
+
+/* A function that calls add() and has a good place for a breakpoint */
+fun compute(n)
+  arr = [10, 20, 30, 40, 50]
+  i = 2
+  // BREAKPOINT CANDIDATE (LINE_BK_1): set a breakpoint on the next line:
+  x = arr[i] + 7
+  add(x, n)
+
+/* A function that intentionally triggers a runtime error (index out of range) */
+fun crash()
+  nums = [1, 2, 3]
+  // This out-of-range access triggers an error and drops into the REPL:
+  print(nums[10])
+
+fun main()
+  compute(3)
+  crash()
+
+main()
+
+/* Expected when run with --repl-on-error (your version and line/ip may vary):
+Runtime error: index out of range
+ (at ./examples/debug_reporting.fun:XX in crash, op INDEX_GET @ip YY)
+Entering REPL due to runtime error (code 1)
+Fun VERSION REPL
+Type :help for commands. Submit an empty line to run.
+fun> :backtrace
+Backtrace (most recent call first):
+  #TOP crash at ./examples/debug_reporting.fun ip=... line=...
+  #... main at ./examples/debug_reporting.fun ip=... line=...
+fun> :list
+>    <current line> ...
+fun> :locals
+  0: [locals if any]
+fun> :disas
+>      ip: OP_NAME OPERAND
+       ...
+fun> :stack
+[... stack values ...]
+
+Then try breakpoints and stepping on a new run:
+fun> :break ./examples/debug_reporting.fun:<line for LINE_BK_1>
+fun> :info breaks
+fun> :cont
+... Breakpoint hit ...
+fun> :next
+fun> :finish
+fun> :cont
+*/