vinnie357 whamm-dsl — The .mm Monitor Language
A .mm script is the instrumentation program whamm! injects into a WebAssembly binary (or compiles for engine-support). Each script contains global declarations followed by one or more probes. whamm! statically analyses match rules to decide which probes apply at each site, folding away constant guards before injection.
For installing whamm! and running instrumented modules, load the companion whamm skill in this plugin.
Script structure
A .mm file contains, in order:
usedeclarations —use lib;imports a named library.- Global variable declarations —
report var,var, etc. declared at file scope. - Function definitions —
name(args) -> ret { .. }(NOT YET IMPLEMENTED). - Probes — one or more match-rule blocks, each optionally gated by a predicate.
Match rules
provider:package:event:mode / predicate / { actions }
The predicate is optional. Without it: provider:package:event:mode { actions }.
Hierarchy: wasm (provider) → package → event → mode.
| Package | Events | Modes |
|---|---|---|
opcode |
any opcode name or glob | before, after, alt |
func |
(any function) | entry, exit (unwind planned) |
block |
end |
(none) |
| (none) | begin, end, report |
(none — top-level probes) |
Globbing examples:
wasm:opcode:*:before # all opcodes, before
wasm::*if:before # if + br_if (empty package = wildcard)
wasm:opcode:*load*|*store*:before # all memory loads and stores
wasm:opcode:call|return_call:before
Type bounds narrow polymorphic args: wasm:opcode:call(arg0: i32):before matches only call sites where arg0 is i32.
Full event and bound-variable tables: see references/events.md.
Predicated probes & modes
wasm:opcode:call:before / pc == 25 && arg0 == 1 / {
count++;
}
whamm! performs constant folding on static vars (pc, fid, imm0, …). At a site where pc != 25, the probe is not injected at all. At pc == 25 the dynamic guard arg0 == 1 is emitted inline.
Modes:
before— inject before the opcode executes.after— inject after; result varsres0,res1, … hold the opcode's outputs.alt— replace the opcode; calldrop_args()to discard its input args.entry/exit— inject at function entry or exit.
Variables
| Kind | Declared as | Lifetime | Typical use |
|---|---|---|---|
var |
var x: T; or var x: T = v; |
Reinitialised on each probe invocation | Temporaries |
unshared var |
unshared var x: T; |
One instance per match site; retained across visits | Per-callsite counters |
report var |
report var x: T; |
Alias for report unshared var; printed at program end via WASI |
Output accumulators |
frame var |
frame var x: T; |
Stored on the function frame; shared between func:entry and func:exit |
Entry→exit state |
shared var |
shared var x: T; |
Single instance across ALL sites | NOT YET IMPLEMENTED |
Variables declared inside a probe body behave as unshared var by default.
Full type syntax — ints, floats, str, tuples, maps: see references/language.md.
A first script
Count every WebAssembly opcode executed:
report var count: u32;
wasm:opcode:*:before {
count++;
}
report var is global and printed automatically when the instrumented module exits (via WASI). No wasm:report block required for simple scalars.
Verifying bound variables
The bound-variable lists in this skill are derived from the whamm documentation. Per /core:anti-fabrication, confirm the exact variables available at a given match rule with whamm info --rule "<rule>" at the installed version rather than assuming — the authoritative set is what the binary reports.
References
references/language.md— types, var kinds with examples, operators, strings, tuples, maps; functions (planned)references/events.md— full provider hierarchy, available vs planned, all bound-variable tablesreferences/libraries.md—use, whamm_core built-ins, string memory interop,@static/@init,wasm:reportoverridereferences/examples.md— annotated.mmscripts: instruction count, branch monitor, call graph, cache simulator, string interop
Companion skill for install and CLI: whamm (same plugin).