[mojo][core] Update the codebase to mojo v1.0.0b2

.github/actions/setup-decimo/action.yml

@@ -1,17 +1,17 @@
 name: Setup Decimo with Pixi
-description: Install pixi (cached), activate the Mojo environment, and download the prebuilt decimo.mojopkg artifact into tests/.
+description: Install pixi (cached), activate the Mojo environment, and download the prebuilt decimo.mojoc artifact into tests/.
 
 runs:
   using: composite
   steps:
     - uses: prefix-dev/setup-pixi@v0.9.5
       with:
         activate-environment: true
-    - name: Download decimo.mojopkg artifact
+    - name: Download decimo.mojoc artifact
       uses: actions/download-artifact@v4
       with:
-        name: decimo-mojopkg
+        name: decimo-mojoc
         path: .
     - name: Stage package next to tests
       shell: bash
-      run: cp decimo.mojopkg tests/
+      run: cp decimo.mojoc tests/

.github/workflows/run_tests.yaml

@@ -15,9 +15,9 @@ defaults:
     shell: bash
 
 # The `build` job is the gate: format check, doc generation, and the
-# `decimo.mojopkg` build all run once. The package is uploaded as an
+# `decimo.mojoc` build all run once. The package is uploaded as an
 # artifact so downstream test jobs can download it instead of rebuilding
-# (saves ~30s of `mojo package` per job × 10 jobs). The pixi environment
+# (saves ~30s of `mojo precompile` per job × 10 jobs). The pixi environment
 # is cached by `prefix-dev/setup-pixi@v0.9.5`, so test jobs no longer
 # `curl | sh` and `pixi install` from scratch.
 
@@ -41,7 +41,7 @@ jobs:
         run: |
           for attempt in 1 2 3; do
             echo "=== build attempt $attempt ==="
-            if pixi run mojo package src/decimo; then
+            if pixi run mojo precompile src/decimo -o decimo.mojoc; then
               echo "=== build succeeded on attempt $attempt ==="
               break
             fi
@@ -52,13 +52,13 @@ jobs:
             echo "=== build crashed, retrying in 5s... ==="
             sleep 5
           done
-      - name: Stage decimo.mojopkg next to tests
+      - name: Stage decimo.mojoc next to tests
         # `pixi run doc` documents `src/cli/calculator`, which imports
-        # `decimo.*`. Mojo 1.0.0b1 cannot resolve those qualified
+        # `decimo.*`. Mojo cannot resolve those qualified
         # references when re-traversing the source tree via `-I src`,
         # so the doc task uses `-I tests` against the prebuilt
-        # `decimo.mojopkg`. Stage it here before invoking doc.
-        run: cp decimo.mojopkg tests/
+        # `decimo.mojoc`. Stage it here before invoking doc.
+        run: cp decimo.mojoc tests/
       - name: Generate docs (with retry for Mojo compiler intermittent crashes)
         run: |
           for attempt in 1 2 3; do
@@ -74,13 +74,13 @@ jobs:
             echo "=== doc crashed, retrying in 5s... ==="
             sleep 5
           done
-      - name: Verify decimo.mojopkg was produced
-        run: test -f decimo.mojopkg
-      - name: Upload decimo.mojopkg artifact
+      - name: Verify decimo.mojoc was produced
+        run: test -f decimo.mojoc
+      - name: Upload decimo.mojoc artifact
         uses: actions/upload-artifact@v4
         with:
-          name: decimo-mojopkg
-          path: decimo.mojopkg
+          name: decimo-mojoc
+          path: decimo.mojoc
           retention-days: 1
           if-no-files-found: error
 
@@ -287,7 +287,7 @@ jobs:
           done
 
   # ── Test: CLI ────────────────────────────────────────────────────────────────
-  # The CLI test needs a freshly built binary, not the .mojopkg, so we
+  # The CLI test needs a freshly built binary, not the .mojoc, so we
   # invoke `pixi run buildcli` here. Uses cached pixi env (no curl install,
   # no second `pixi install` from scratch).
   test-cli:
@@ -316,13 +316,13 @@ jobs:
             echo "=== build crashed, retrying in 5s... ==="
             sleep 5
           done
-      - name: Stage decimo.mojopkg next to tests
+      - name: Stage decimo.mojoc next to tests
         # `tests/test.sh run_cli` and `run_bigfloat` use `-I tests` to load
-        # the prebuilt `decimo.mojopkg` (Mojo 1.0.0b1's `mojo run/build`
+        # the prebuilt `decimo.mojoc` (Mojo's `mojo run/build`
         # cannot resolve `decimo.X.Y.foo` qualified references when
         # re-traversing source via `-I src`). `pixi run buildcli` produces
-        # the package at `temp/decimo.mojopkg`, so stage a copy here.
-        run: cp temp/decimo.mojopkg tests/
+        # the package at `temp/decimo.mojoc`, so stage a copy here.
+        run: cp temp/decimo.mojoc tests/
       - name: Run tests (with retry for Mojo compiler intermittent crashes)
         run: |
           for attempt in 1 2 3; do

.gitignore

@@ -10,8 +10,9 @@
 .magic
 magic.lock
 
-# mojopkg files
+# mojo pre-compiled files
 *.mojopkg
+*.mojoc
 
 # Editor environments
 .vscode

docs/changelog.md

@@ -4,6 +4,12 @@ This is a list of changes for the Decimo package (formerly DeciMojo).
 
 ## Unreleased
 
+1. **Migrated the codebase to Mojo v1.0.0b2.** Bumped the Pixi `mojo`
+   dependency to `>=1.0.0b2` and `argmojo` to `0.7.0`. Switched packaging
+   from the deprecated `mojo package` / `.mojopkg` to `mojo precompile` /
+   `.mojoc` across Pixi tasks, CI workflows, and helper scripts, and
+   updated the `Decimal128` string formatter to the
+   `StringSlice(unsafe_from_utf8=Span(...))` constructor (PR #257).
 1. **Renamed `BigDecimal` rounding APIs to `*_inplace`.**
    The free function `decimo.bigdecimal.rounding.round_to_precision` and
    the `BigDecimal.round_to_precision` method were renamed to

docs/plans/gmp_integration.md

@@ -813,8 +813,8 @@ Link against whichever is present. The stub library lets Decimo compile and run
 
 **Phase 1 (immediate)**: Use **Option A** — compile-time feature flag. Build two package variants:
 
-- `decimo.mojopkg` — native only (default)
-- `decimo_gmp.mojopkg` — with GMP backend
+- `decimo.mojoc` — native only (default)
+- `decimo_gmp.mojoc` — with GMP backend
 
 **Phase 2 (when Mojo matures)**: Migrate to **Option B** with `DLHandle` when available, enabling true runtime detection.
 
@@ -1132,7 +1132,7 @@ build-gmp-wrapper = """
 
 package-with-gmp = { depends-on = ["build-gmp-wrapper"] }
 package-with-gmp.cmd = """
-    mojo package src/decimo -o decimo.mojopkg && \
+    mojo precompile src/decimo -o decimo.mojoc && \
     cp src/decimo/gmp/libgmp_wrapper.dylib .
 """
 ```

docs/plans/mojo4py.md

@@ -12,7 +12,7 @@
 
 Modular has introduced a beta mechanism that allows Mojo code to be exposed as a standard CPython extension module (`.so` / `.dylib`). This means a Python user can write `import decimo` and get access to Mojo-native `Decimal128`, `BigDecimal`, `BigInt`, and `BigUint` types at near-native speed, without rewriting anything in Python.
 
-**Feasibility verdict: Possible but non-trivial.** The main (no surprise) blocker is that decimo is a *packaged* Mojo library (`.mojopkg`), not a single `.mojo` file. The Mojo importer hook (the easy dev-time path) does not support custom import paths for non-stdlib Mojo packages. The `.so` build path (the distribution path) works fine. This means the developer workflow is slightly more manual, but distribution is fully viable.
+**Feasibility verdict: Possible but non-trivial.** The main (no surprise) blocker is that decimo is a *packaged* Mojo library (`.mojoc`), not a single `.mojo` file. The Mojo importer hook (the easy dev-time path) does not support custom import paths for non-stdlib Mojo packages. The `.so` build path (the distribution path) works fine. This means the developer workflow is slightly more manual, but distribution is fully viable.
 
 ---
 
@@ -25,7 +25,7 @@ Modular has introduced a beta mechanism that allows Mojo code to be exposed as a
 | **Source import hook** | `import mojo.importer` in Python, then `import mojo_module` (auto-compiles `.mojo` → `.so` into `__mojocache__/`) | Dev prototyping with single-file modules only |
 | **Pre-built `.so`**    | `mojo build mojo_module.mojo --emit shared-lib -o mojo_module.so`                                                 | Production, packages with dependencies, CI/CD |
 
-For decimo, **only the pre-built `.so` path is viable** because the binding code will `import decimo` (the `.mojopkg`), and the importer hook cannot resolve that path.
+For decimo, **only the pre-built `.so` path is viable** because the binding code will `import decimo` (the `.mojoc`), and the importer hook cannot resolve that path.
 
 ### 2.2 The Binding Pattern
 
@@ -183,7 +183,7 @@ tpy     = "clear && pixi run testpy"
 wheel   = "cd python && pixi run python -m build --wheel"
 ```
 
-- `pixi run buildpy` — compiles the Mojo binding directly into the installable package at `python/src/decimo/_decimo.so`. No need to pre-package `decimo.mojopkg`; the `-I src` flag resolves `import decimo` to `src/decimo/`.
+- `pixi run buildpy` — compiles the Mojo binding directly into the installable package at `python/src/decimo/_decimo.so`. No need to pre-package `decimo.mojoc`; the `-I src` flag resolves `import decimo` to `src/decimo/`.
 - `pixi run testpy` — builds then runs the Python test suite.
 - `pixi run wheel` — produces a pure-Python placeholder wheel in `python/dist/` (no `.so` included); suitable for PyPI name reservation.
 

docs/readme_unreleased.md

@@ -400,7 +400,7 @@ Bug reports and feature requests are welcome! If you encounter issues, please [f
 ```text
 decimo/
 ├── src/                          # All source code
-│   ├── decimo/                   # Core library (mojo package)
+│   ├── decimo/                   # Core library (mojo precompile)
 │   │   ├── bigdecimal/           #   Arbitrary-precision decimal (Decimal)
 │   │   ├── bigint/               #   Arbitrary-precision signed integer (Integer)
 │   │   ├── bigint10/             #   Base-10 signed integer (BigInt10)
@@ -409,7 +409,7 @@ decimo/
 │   │   └── ...                   #   Shared utilities (str, errors, rounding)
 │   └── cli/                      # CLI calculator application
 │       ├── main.mojo             #   Entry point (ArgMojo CLI)
-│       └── calculator/           #   Calculator engine (mojo package)
+│       └── calculator/           #   Calculator engine (mojo precompile)
 │           ├── tokenizer.mojo    #     Lexer: expression → tokens
 │           ├── parser.mojo       #     Shunting-yard: infix → RPN
 │           └── evaluator.mojo    #     RPN evaluator using Decimal
@@ -425,7 +425,7 @@ decimo/
 └── pixi.toml                     # Project configuration and tasks
 ```
 
-`src/decimo/` is a Mojo package — it is compiled with `mojo package` and can be imported by external projects. The TOML parser (`decimo.toml`) is included as a subpackage. `src/cli/` is an application that consumes the `decimo` package and compiles to a standalone binary via `mojo build`.
+`src/decimo/` is a Mojo package — it is compiled with `mojo precompile` and can be imported by external projects. The TOML parser (`decimo.toml`) is included as a subpackage. `src/cli/` is an application that consumes the `decimo` package and compiles to a standalone binary via `mojo build`.
 
 ## Tests and benches
 

examples/run_bigfloat.sh

@@ -8,7 +8,7 @@
 #
 # What it does:
 #   1. Ensures the GMP/MPFR C wrapper (libdecimo_gmp_wrapper) is built.
-#   2. Ensures tests/decimo.mojopkg is available (built on demand).
+#   2. Ensures tests/decimo.mojoc is available (built on demand).
 #   3. Builds <file.mojo> with `-I tests`, debug info, and ASSERT=all,
 #      linking against the C wrapper. Output binary goes to temp/<name>.
 #   4. Executes the binary with DYLD_LIBRARY_PATH / LD_LIBRARY_PATH set
@@ -43,10 +43,10 @@ if [[ ! -f "$WRAPPER_LIB" ]]; then
     bash "$WRAPPER_DIR/build_gmp_wrapper.sh"
 fi
 
-# 2. Ensure decimo.mojopkg exists for `-I tests`.
-if [[ ! -f tests/decimo.mojopkg ]]; then
-    echo "==> Building tests/decimo.mojopkg..."
-    pixi run mojo package src/decimo -o tests/decimo.mojopkg
+# 2. Ensure decimo.mojoc exists for `-I tests`.
+if [[ ! -f tests/decimo.mojoc ]]; then
+    echo "==> Building tests/decimo.mojoc..."
+    pixi run mojo precompile src/decimo -o tests/decimo.mojoc
 fi
 
 # 3. Build the user's .mojo file into temp/<basename>.