Add Nockchain gRPC contact example.

crates/goth-eval/src/eval.rs

@@ -647,6 +647,7 @@ fn prim_arity(prim: PrimFn) -> usize {
         PrimFn::Neg | PrimFn::Abs | PrimFn::Not | PrimFn::Exp | PrimFn::Ln | PrimFn::Sqrt | PrimFn::Sin | PrimFn::Cos | PrimFn::Tan | PrimFn::Floor | PrimFn::Ceil | PrimFn::Round | PrimFn::Sum | PrimFn::Prod | PrimFn::Len | PrimFn::Shape | PrimFn::Reverse | PrimFn::Transpose | PrimFn::Norm | PrimFn::ToInt | PrimFn::ToFloat | PrimFn::ToBool | PrimFn::ToChar | PrimFn::ParseInt | PrimFn::ParseFloat | PrimFn::Iota | PrimFn::ToString | PrimFn::Chars => 1,
         PrimFn::Print | PrimFn::Write | PrimFn::ReadLine | PrimFn::ReadKey | PrimFn::ReadFile | PrimFn::Sleep => 1,
         PrimFn::Flush | PrimFn::RawModeEnter | PrimFn::RawModeExit => 1,  // Terminal control (take unit)
+        PrimFn::FromChars => 1,  // [n]Char → String
         PrimFn::Lines | PrimFn::Words | PrimFn::Bytes => 1,  // String splitting (unary)
         PrimFn::Re | PrimFn::Im | PrimFn::Conj | PrimFn::Arg => 1,  // Complex decomposition
         PrimFn::Trace | PrimFn::Det | PrimFn::Inv | PrimFn::Diag | PrimFn::Eye | PrimFn::Eig | PrimFn::EigVecs => 1,  // Matrix utilities

examples/README.md

@@ -277,6 +277,32 @@ cargo run --quiet --package goth-cli -- ../examples/crypto/hashfile.goth /tmp/te
 
 ---
 
+## json/
+
+JSON parsing and serialization — pure Goth implementation using recursive descent parsing and fold-based serialization. All functions are implemented entirely in Goth via the `json.goth` standard library.
+
+| File | Description | Example |
+|------|-------------|---------|
+| `parse_simple.goth` | Parse JSON, extract fields, serialize | `parseJson "{\"name\":\"Goth\"}" → ⟨⊤, ..., ""⟩` |
+| `roundtrip.goth` | Parse → serialize → re-parse roundtrip test | `toJson (parseJson input).1` |
+
+```sh
+# Parse and extract fields from JSON
+cargo run --quiet --package goth-cli -- ../examples/json/parse_simple.goth
+# Name: Goth
+# Version: 1
+# Features: 3
+# ...
+
+# Roundtrip: parse → serialize → parse → serialize
+cargo run --quiet --package goth-cli -- ../examples/json/roundtrip.goth
+# Roundtrip: PASS
+```
+
+**Demonstrates:** Recursive descent parsing, `chars`, `fromChars`, `parseFloat`, fold-based string building, tagged tuples as sum types, `strEq`, `use` imports.
+
+---
+
 ## Language Features Covered
 
 | Feature | Examples |
@@ -291,13 +317,13 @@ cargo run --quiet --package goth-cli -- ../examples/crypto/hashfile.goth /tmp/te
 | Sum/Product (`Σ`/`Π`) | numeric, higher-order, simulation |
 | Iota (`ι`) | numeric, simulation |
 | Array concat (`⊕`) | higher-order |
-| String concat (`⧺`) | simulation, crypto |
+| String concat (`⧺`) | simulation, crypto, json |
 | Conditionals (`if/then/else`) | basic, recursion, algorithms |
 | Contracts (`⊢`/`⊨`) | contracts, random |
 | Uncertainty (`±`) | uncertainty |
 | File I/O (`▷`, `writeFile`, `readFile`) | io, simulation, crypto |
-| Module imports (`use`) | simulation, random, crypto |
+| Module imports (`use`) | simulation, random, crypto, json |
 | Tail-call optimization | tco |
 | Bitwise ops (`bitand`, `bitor`, `bitxor`, `shl`, `shr`) | crypto |
-| Tuple destructuring (`⟨a, b⟩`) | random |
+| Tuple destructuring (`⟨a, b⟩`) | random, json |
 | PRNG / entropy | random |

examples/json/parse_simple.goth

@@ -0,0 +1,19 @@
+# JSON Parsing Example
+# Parse a JSON string and extract fields
+use "../../stdlib/json.goth"
+
+╭─ main : () → String
+╰─ let input = "{\"name\":\"Goth\",\"version\":1.0,\"features\":[\"arrays\",\"tuples\",\"unicode\"],\"stable\":true}"
+   in let result = parseJson input
+   in if ¬(result.0) then "Parse error: " ⧺ result.2
+   else let json = result.1
+   in let nameOpt = jsonGet "name" json
+   in let nameLine = if nameOpt.0 then "Name: " ⧺ asStr nameOpt.1 else "No name"
+   in let verOpt = jsonGet "version" json
+   in let verLine = if verOpt.0 then "Version: " ⧺ toString (asNum verOpt.1) else "No version"
+   in let featOpt = jsonGet "features" json
+   in let featLine = if featOpt.0 then "Features: " ⧺ toString (jsonLen featOpt.1) else "No features"
+   in let stableOpt = jsonGet "stable" json
+   in let stableLine = if stableOpt.0 then "Stable: " ⧺ toString (asBool stableOpt.1) else "No stable"
+   in let serialized = toJson json
+   in nameLine ⧺ "\n" ⧺ verLine ⧺ "\n" ⧺ featLine ⧺ "\n" ⧺ stableLine ⧺ "\n" ⧺ "Serialized: " ⧺ serialized

examples/json/roundtrip.goth

@@ -0,0 +1,18 @@
+# JSON Roundtrip Example
+# Parse JSON, serialize back, and compare
+use "../../stdlib/json.goth"
+
+╭─ main : () → String
+╰─ let input = "{\"a\":1,\"b\":[2,3],\"c\":{\"d\":true},\"e\":null,\"f\":\"hello\\nworld\"}"
+   in let r1 = parseJson input
+   in if ¬(r1.0) then "Parse error: " ⧺ r1.2
+   else let serialized = toJson r1.1
+   in let r2 = parseJson serialized
+   in if ¬(r2.0) then "Re-parse error: " ⧺ r2.2
+   else let serialized2 = toJson r2.1
+   in "Input:      " ⧺ input ⧺ "\n"
+      ⧺ "Serialized: " ⧺ serialized ⧺ "\n"
+      ⧺ "Re-serial:  " ⧺ serialized2 ⧺ "\n"
+      ⧺ if strEq serialized serialized2
+        then "Roundtrip: PASS"
+        else "Roundtrip: FAIL"

examples/nockchain/balance.goth

@@ -0,0 +1,12 @@
+# Query wallet balance via nockchain-bridge
+# Usage: nockchain-bridge examples/nockchain/balance.goth <address>
+#
+# The bridge spawns this program, pipes its stdout as commands,
+# and feeds gRPC responses back via stdin.
+#
+# Protocol: print "BALANCE <addr>", readLine → "OK <nicks>" or "ERROR <msg>"
+
+╭─ main : String → ()
+╰─ let _ = print ("BALANCE " ⧺ ₀) in
+   let resp = readLine ⟨⟩ in
+   print (words resp)

examples/nockchain/blocks.goth

@@ -0,0 +1,10 @@
+# List recent blocks from Nockchain
+# Usage: nockchain-bridge examples/nockchain/blocks.goth
+#
+# Sends GET_BLOCKS, reads multi-line response (each line: OK <height> <id> <ts>),
+# terminated by a blank line.
+
+╭─ main : I64 → ()
+╰─ let _ = print "GET_BLOCKS" in
+   let resp = readLine ⟨⟩ in
+   print resp

examples/nockchain/tx_status.goth

@@ -0,0 +1,9 @@
+# Check if a transaction has been accepted
+# Usage: nockchain-bridge examples/nockchain/tx_status.goth <tx_id>
+#
+# Protocol: print "TX_ACCEPTED <txid>", readLine → "OK true|false" or "ERROR <msg>"
+
+╭─ main : String → ()
+╰─ let _ = print ("TX_ACCEPTED " ⧺ ₀) in
+   let resp = readLine ⟨⟩ in
+   print resp