feat!: Change the return type of measurement functions to a new `Measurement` type and remove opaque bools from the compiler by tatiana-s · Pull Request #1707 · Quantinuum/guppylang

tatiana-s · 2026-04-30T10:36:52Z

Requires a breaking tket release with the extension changes in #1558 before this can be merged

BREAKING CHANGE: (guppylang.std.quantum): measure (and measure_array by extension) now return Measurement instead of bool
BREAKING CHANGE: (guppylang.std.qsystem/qsystem.functional): measure and measure_reset (and by extension the array versions) now return Measurement instead of bool (this matches the behaviour of lazy_measure/lazy_measure_and_reset)
BREAKING CHANGE: (guppylang_internals): bool is now lowered to ht.Bool again instead of tket.bool

The deferred_measurement.ipynb notebook has been adjusted to explain the motivation for the lazy behaviour instead of contrasting measure and lazy_measure

…nt type

# Conflicts: # guppylang/src/guppylang/std/qsystem/__init__.py # guppylang/src/guppylang/std/qsystem/functional.py

hugrbot · 2026-05-05T09:26:46Z

This PR contains breaking changes to the public Python API.

Breaking changes summary

guppylang/src/guppylang/std/qsystem/__init__.py:0: collect_measurements:
Public object was removed

guppylang-internals/src/guppylang_internals/definition/custom.py:0: BoolOpCompiler:
Public object was removed

guppylang-internals/src/guppylang_internals/compiler/expr_compiler.py:0: ARRAY_READ_BOOL:
Public object was removed

guppylang-internals/src/guppylang_internals/compiler/expr_compiler.py:0: ARRAY_MAKE_OPAQUE_BOOL:
Public object was removed

guppylang-internals/src/guppylang_internals/compiler/expr_compiler.py:0: array_read_bool:
Public object was removed

guppylang-internals/src/guppylang_internals/compiler/expr_compiler.py:0: array_make_opaque_bool:
Public object was removed

guppylang-internals/src/guppylang_internals/compiler/expr_compiler.py:0: apply_array_op_with_conversions:
Public object was removed

guppylang-internals/src/guppylang_internals/tys/builtin.py:214: bool_type_def:
Attribute value was changed:
Old: OpaqueTypeDef(id=(DefId.fresh()), name='bool', defined_at=None, params=[], never_copyable=False, never_droppable=False, to_hugr=(lambda args, ctx: OpaqueBool))
New: OpaqueTypeDef(id=(DefId.fresh()), name='bool', defined_at=None, params=[], never_copyable=False, never_droppable=False, to_hugr=(lambda args, ctx: ht.Bool))

github-actions · 2026-05-05T09:27:57Z

Bencher Report

Branch	ts/future-measure
Testbed	Linux

Click to view all benchmark results

Benchmark	hugr_bytes	Benchmark Result bytes x 1e3 (Result Δ%)	Upper Boundary bytes x 1e3 (Limit %)	hugr_nodes	Benchmark Result nodes (Result Δ%)	Upper Boundary nodes (Limit %)
tests/benchmarks/test_big_array.py::test_big_array_compile	📈 view plot 🚷 view threshold	158.29 x 1e3 (-0.30%) Baseline: 158.77 x 1e3	160.36 x 1e3 (98.71%)	📈 view plot 🚷 view threshold	6,630.00 (-0.17%) Baseline: 6,641.00	6,707.41 (98.85%)
tests/benchmarks/test_ctrl_flow.py::test_many_ctrl_flow_compile	📈 view plot 🚷 view threshold	26.98 x 1e3 (-2.00%) Baseline: 27.53 x 1e3	27.81 x 1e3 (97.03%)	📈 view plot 🚷 view threshold	1,051.00 (-2.14%) Baseline: 1,074.00	1,084.74 (96.89%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_benchmark_compile	📈 view plot 🚷 view threshold	10.08 x 1e3 (-7.61%) Baseline: 10.91 x 1e3	11.02 x 1e3 (91.48%)	📈 view plot 🚷 view threshold	300.00 (-2.60%) Baseline: 308.00	311.08 (96.44%)
tests/benchmarks/test_queue_push_pop.py::test_queue_push_pop_benchmark_compile	📈 view plot 🚷 view threshold	13.88 x 1e3 (-6.44%) Baseline: 14.84 x 1e3	14.99 x 1e3 (92.64%)	📈 view plot 🚷 view threshold	423.00 (-2.76%) Baseline: 435.00	439.35 (96.28%)

🐰 View full continuous benchmarking report in Bencher

codspeed-hq · 2026-05-05T09:43:39Z

Merging this PR will not alter performance

✅ 9 untouched benchmarks

_{Comparing ts/future-measure (9405b97) with main (17282cd)}

# Conflicts: # pyproject.toml # uv.lock

codecov-commenter · 2026-05-20T10:10:46Z

Codecov Report

❌ Patch coverage is 86.15385% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.89%. Comparing base (dcc1ed1) to head (9405b97).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
guppylang/src/guppylang/std/qsystem/__init__.py	65.00%	7 Missing ⚠️
guppylang/src/guppylang/std/quantum/__init__.py	88.23%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1707      +/-   ##
==========================================
- Coverage   93.49%   92.89%   -0.61%     
==========================================
  Files         133      134       +1     
  Lines       12793    12935     +142     
==========================================
+ Hits        11961    12016      +55     
- Misses        832      919      +87

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maximilianruesch

Big PR, lots of little changes. Great work! I massively trust the tests on this one.

A few comments here and there. Also I think the title (which will end up as the commit title) should mention that we drop the opaque guppy bools / that we change the return type of measurement functions, not just add some type.

maximilianruesch · 2026-05-20T15:54:17Z

 # TODO this should be a compile-time error
+# Fails with "pyo3_runtime.PanicException: Cannot convert negative integer -2 to
+# unsigned."
+@pytest.mark.xfail(reason="Rust PanicException cannot be caught from Python")


You can catch "Exception", and PanicException should be a subtype of that

I did try that and it didn't work?

What do you mean by "it did not work"? The panic went through? You can also catch BaseException even more generally...

maximilianruesch · 2026-05-21T09:34:57Z

   "metadata": {},
   "source": [
-    "Simply replacing the method results in an error because `lazy_measure` returns a value of type `Measurement`. In order to obtain a `bool`, we have to explicitaly use `read()` on the value. "
+    "Simply replacing the method results in an error because `result` expects a `bool`. In order to obtain it, we have to explicitly use `read()` on the value of type `Measurement`. This will block until the physical measurement is completed:"


We are not "replacing" the method anymore, since we are breakingly forcing an upgrade. This needs a reword, potentially to just "This results in an error because ...".

maximilianruesch

LGTM for now. When merging / handling the latest tket release, please rerequest a review, and then I can approve.

maximilianruesch · 2026-05-26T12:42:02Z

    "    qs = array(some(qubit()) for _ in range(3))\n",
    "    mask = array(True, False, True)\n",
-    "    measure_mask(qs, mask)\n",
+    "    # We need to consume the array of measurement options as they are linear.\n",


This comment and the next one have the same underlying reason (linear -> cannot be leaked), but both only display the truth partially.

acl-cqc · 2026-05-27T10:38:13Z


+@guppy
+@no_type_check
+def collect_measurements(


I guess it's been called collect_measurements for awhile but it feels like it ought to have read in the name at least, given the measurements are already in a collection (so no collecting is done) and there's nothing in the name to say that it's reading!!

acl-cqc

Thanks @tatiana-s! A big PR already I admit but is this the time to add overrides to result that accept Measurement directly? (Or a followup?)

tatiana-s added 7 commits April 9, 2026 16:43

WIP revert opaque bool and change measure ops result to new measureme…

1f2c200

…nt type

WIP Adjusting lots of tests mainly

db8fd32

More test fixes

892ec84

Merge remote-tracking branch 'origin/main' into ts/future-measure

eb11e3f

# Conflicts: # guppylang/src/guppylang/std/qsystem/__init__.py # guppylang/src/guppylang/std/qsystem/functional.py

Fix merge issues + execute notebooks properly + some refactoring

3a48199

Update notebook text

9dcf9f8

Revert devenv.lock to main version

a2889a7

tatiana-s requested a review from a team as a code owner April 30, 2026 10:36

tatiana-s requested a review from mark-koch April 30, 2026 10:36

tatiana-s and others added 3 commits April 30, 2026 11:41

Remove monohugr dependencies

5350569

Add hugrenv (temporarily) for off-release tket2 wheel builds

d5551f1

Merge branch 'main' into ts/future-measure

ce1fe56

tatiana-s added 6 commits May 6, 2026 16:27

Try with qis-compiler dependency

13c5102

# Conflicts: # pyproject.toml # uv.lock

Merge remote-tracking branch 'origin/main' into ts/future-measure

d9291a7

# Conflicts: # pyproject.toml # uv.lock

Add back branch dependencies

f3ea7f9

Remove bool extension

541e099

Merge remote-tracking branch 'origin/main' into ts/future-measure

1ab6ec6

Ignore pytket measure tests for now

e23ef39

ss2165 requested review from maximilianruesch and removed request for mark-koch May 18, 2026 09:07

tatiana-s added 3 commits May 20, 2026 10:35

xfail test_int_to_nat_negative panic exception

ded8e96

Merge remote-tracking branch 'origin/main' into ts/future-measure

b5c1927

Adjust to qsystem extension changes

e53349b

maximilianruesch requested changes May 21, 2026

View reviewed changes

Address comments

ec5ea14

tatiana-s changed the title ~~feat!: Add a Measurement type as the return type for measurement functions~~ feat!: Change the return type of measurement functions to a new Measurement type and remove opaque bools from the compiler May 22, 2026

Delete deferred measurement example

9405b97

tatiana-s requested a review from maximilianruesch May 26, 2026 09:59

maximilianruesch requested changes May 26, 2026

View reviewed changes

tatiana-s added the S-wait-to-merge Status: Ready to merge but waiting on external factor label May 26, 2026

acl-cqc reviewed May 27, 2026

View reviewed changes

acl-cqc mentioned this pull request May 27, 2026

feat!: Add measurement extension and change tket.quantum / tket.qsystem extension measurement ops return type Quantinuum/tket2#1558

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