Tricu 2.0.0

Sorry for squashing all of this but 🤷

demos/viewContracts/frontendEmission/README.md

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+# Frontend Emission Demos
+
+These examples show the layer between source-level View annotations and the
+portable View Contract checker.
+
+Each `*.source.txt` file is pseudo-source: it is not parsed by `tricu`. It shows
+the information a frontend has after parsing/elaboration.
+
+Each matching `*.emitted.tri` file shows the lowered typed-program metadata that
+a frontend can emit today. A successful check returns checked-exec; these demos
+focus on structural Views, so they report `"ok"` as soon as metadata checking
+succeeds. Guarded programs should run the returned checked-exec with
+`runChecked`, as shown in `demos/viewContracts.tri` and by `tricu check`.
+
+## Successful map use
+
+Pseudo-source:
+
+```text
+map : Fn [Fn [Bool] String, List Bool] (List String)
+f   : Fn [Bool] String
+xs  : List Bool
+
+partial = map f
+out     = partial xs
+
+require out : List String
+```
+
+Run the emitted artifact:
+
+```bash
+tricu eval demos/viewContracts/frontendEmission/map-success.emitted.tri -f decode
+```
+
+Expected output:
+
+```text
+"ok"
+```
+
+## Wrong list argument
+
+Pseudo-source:
+
+```text
+map : Fn [Fn [Bool] String, List Bool] (List String)
+f   : Fn [Bool] String
+xs  : List String
+
+partial = map f
+out     = partial xs
+```
+
+Run:
+
+```bash
+tricu eval demos/viewContracts/frontendEmission/map-wrong-list.emitted.tri -f decode
+```
+
+Expected output:
+
+```text
+"symbol 162 expected List Bool but got List String"
+```
+
+## Wrong filter predicate
+
+Pseudo-source:
+
+```text
+filter : Fn [Fn [Bool] Bool, List Bool] (List Bool)
+pred   : Fn [Bool] String
+xs     : List Bool
+
+partial = filter pred
+out     = partial xs
+```
+
+Run:
+
+```bash
+tricu eval demos/viewContracts/frontendEmission/filter-wrong-predicate.emitted.tri -f decode
+```
+
+Expected output:
+
+```text
+"symbol 181 expected Fn [Bool] Bool but got Fn [Bool] String"
+```
+
+## Lowering shape
+
+A frontend does not need to expose `tricu` syntax internally. It only needs to
+emit portable typed-program nodes:
+
+```text
+typedValue symbol view term
+typedApply out callee arg term
+typedRequire symbol view term
+```
+
+The source-level flow:
+
+```text
+out = map f xs
+```
+
+lowers to curried Tree Calculus application nodes:
+
+```text
+typedApply partial map f partialTerm
+typedApply out partial xs outTerm
+```
+
+Function Views drive argument checking and result inference.