Support mixed-dimension arrays [][n]TYPE

CLAUDE.md

@@ -119,8 +119,11 @@ Six packages, one pipeline:
 | `cs[i][j] ? x` | `x = <-cs[i][j]` (multi-dim channel index) |
 | `[3][4]INT grid:` | `grid := make([][]int, 3)` + nested init loops |
 | `grid[i][j] := 42` | `grid[i][j] = 42` (multi-dim array index) |
+| `VAL [][2]INT x IS [[1,2]]:` | `var x [][]int = [][]int{{1, 2}}` (mixed-dim abbreviation) |
+| `VAL [][]INT x IS [[1,2]]:` | `var x [][]int = [][]int{{1, 2}}` (multi-dim open abbreviation) |
 | `PROC f([]CHAN OF INT cs)` | `func f(cs []chan int)` |
 | `PROC f([][]CHAN OF INT cs)` | `func f(cs [][]chan int)` (multi-dim chan array) |
+| `PROC f(VAL [][2]BYTE cfg)` | `func f(cfg [][]byte)` (mixed-dim param) |
 | `PROC f([]CHAN OF INT cs?)` | `func f(cs []chan int)` (direction dropped for array params) |
 | `PROC f([]CHAN OF INT cs!)` | `func f(cs []chan int)` (direction dropped for array params) |
 | `PROC f(CHAN OF INT c?)` | `func f(c <-chan int)` (input/receive-only) |
@@ -191,7 +194,7 @@ Typical workflow for a new language construct:
 
 ## What's Implemented
 
-Preprocessor (`#IF`/`#ELSE`/`#ENDIF`/`#DEFINE`/`#INCLUDE` with search paths, include guards, include-once deduplication, `#COMMENT`/`#PRAGMA`/`#USE` ignored), module file generation from SConscript (`gen-module` subcommand), SEQ, PAR, PRI PAR, IF, WHILE, CASE, ALT, PRI ALT (with guards, timer timeouts, multi-statement bodies with scoped declarations, and replicators using `reflect.Select`), SKIP, STOP, variable/array/channel/timer declarations, abbreviations (`VAL INT x IS 42:`, `INT y IS z:`, `VAL []BYTE s IS "hi":`, untyped `VAL x IS expr:`), assignments (simple and indexed), channel send/receive, channel arrays (`[n]CHAN OF TYPE` with indexed send/receive, `[]CHAN OF TYPE` proc params, and multi-dimensional `[n][m]CHAN`/`[n][m]TYPE`/`[][]CHAN`/`[][]TYPE`), PROC (with VAL, RESULT, reference, CHAN, []CHAN, open array `[]TYPE`, fixed-size array `[n]TYPE`, and shared-type params), channel direction restrictions (`CHAN OF INT c?` → `<-chan int`, `CHAN OF INT c!` → `chan<- int`, call-site annotations `out!`/`in?` accepted), multi-line parameter lists and expressions (lexer suppresses INDENT/DEDENT/NEWLINE inside parens/brackets and after continuation operators), FUNCTION (IS and VALOF forms with multi-statement bodies, including multi-result `INT, INT FUNCTION` with `RESULT a, b`), multi-assignment (`a, b := func(...)` including indexed targets like `x[0], x[1] := x[1], x[0]`), KRoC-style colon terminators on PROC/FUNCTION (optional), INLINE function modifier (accepted and ignored), replicators on SEQ/PAR/IF/ALT (with optional STEP), arithmetic/comparison/logical/AFTER/bitwise operators, type conversions (`INT expr`, `INT16 expr`, `INT32 expr`, `INT64 expr`, `BYTE expr`, `BOOL expr`, `REAL32 expr`, `REAL64 expr`, including BOOL↔numeric via `_boolToInt` helper and `!= 0` comparison, and ROUND/TRUNC qualifiers for float↔int conversions), INT16/INT32/INT64 types, REAL32/REAL64 types, hex integer literals (`#FF`, `#80000000`), string literals, byte literals (`'A'`, `'*n'` with occam escape sequences), built-in print procedures, protocols (simple, sequential, and variant), record types (with field access via bracket syntax), SIZE operator, array slices (`[arr FROM n FOR m]` and shorthand `[arr FOR m]` with slice assignment), array literals (`[1, 2, 3]`), nested PROCs/FUNCTIONs (local definitions as Go closures), MOSTNEG/MOSTPOS (type min/max constants for INT, INT16, INT32, INT64, BYTE, REAL32, REAL64), INITIAL declarations (`INITIAL INT x IS 42:` — mutable variable with initial value), checked (modular) arithmetic (`PLUS`, `MINUS`, `TIMES` — wrapping operators), RETYPES (bit-level type reinterpretation: `VAL INT X RETYPES X :` for float32→int, `VAL [2]INT X RETYPES X :` for float64→int pair), transputer intrinsics (LONGPROD, LONGDIV, LONGSUM, LONGDIFF, NORMALISE, SHIFTRIGHT, SHIFTLEFT — implemented as Go helper functions), CAUSEERROR (maps to `panic("CAUSEERROR")`).
+Preprocessor (`#IF`/`#ELSE`/`#ENDIF`/`#DEFINE`/`#INCLUDE` with search paths, include guards, include-once deduplication, `#COMMENT`/`#PRAGMA`/`#USE` ignored), module file generation from SConscript (`gen-module` subcommand), SEQ, PAR, PRI PAR, IF, WHILE, CASE, ALT, PRI ALT (with guards, timer timeouts, multi-statement bodies with scoped declarations, and replicators using `reflect.Select`), SKIP, STOP, variable/array/channel/timer declarations, abbreviations (`VAL INT x IS 42:`, `INT y IS z:`, `VAL []BYTE s IS "hi":`, untyped `VAL x IS expr:`), assignments (simple and indexed), channel send/receive, channel arrays (`[n]CHAN OF TYPE` with indexed send/receive, `[]CHAN OF TYPE` proc params, and multi-dimensional `[n][m]CHAN`/`[n][m]TYPE`/`[][]CHAN`/`[][]TYPE`/`[][n]TYPE`), PROC (with VAL, RESULT, reference, CHAN, []CHAN, open array `[]TYPE`, fixed-size array `[n]TYPE`, and shared-type params), channel direction restrictions (`CHAN OF INT c?` → `<-chan int`, `CHAN OF INT c!` → `chan<- int`, call-site annotations `out!`/`in?` accepted), multi-line parameter lists and expressions (lexer suppresses INDENT/DEDENT/NEWLINE inside parens/brackets and after continuation operators), FUNCTION (IS and VALOF forms with multi-statement bodies, including multi-result `INT, INT FUNCTION` with `RESULT a, b`), multi-assignment (`a, b := func(...)` including indexed targets like `x[0], x[1] := x[1], x[0]`), KRoC-style colon terminators on PROC/FUNCTION (optional), INLINE function modifier (accepted and ignored), replicators on SEQ/PAR/IF/ALT (with optional STEP), arithmetic/comparison/logical/AFTER/bitwise operators, type conversions (`INT expr`, `INT16 expr`, `INT32 expr`, `INT64 expr`, `BYTE expr`, `BOOL expr`, `REAL32 expr`, `REAL64 expr`, including BOOL↔numeric via `_boolToInt` helper and `!= 0` comparison, and ROUND/TRUNC qualifiers for float↔int conversions), INT16/INT32/INT64 types, REAL32/REAL64 types, hex integer literals (`#FF`, `#80000000`), string literals, byte literals (`'A'`, `'*n'` with occam escape sequences), built-in print procedures, protocols (simple, sequential, and variant), record types (with field access via bracket syntax), SIZE operator, array slices (`[arr FROM n FOR m]` and shorthand `[arr FOR m]` with slice assignment), array literals (`[1, 2, 3]`), nested PROCs/FUNCTIONs (local definitions as Go closures), MOSTNEG/MOSTPOS (type min/max constants for INT, INT16, INT32, INT64, BYTE, REAL32, REAL64), INITIAL declarations (`INITIAL INT x IS 42:` — mutable variable with initial value), checked (modular) arithmetic (`PLUS`, `MINUS`, `TIMES` — wrapping operators), RETYPES (bit-level type reinterpretation: `VAL INT X RETYPES X :` for float32→int, `VAL [2]INT X RETYPES X :` for float64→int pair), transputer intrinsics (LONGPROD, LONGDIV, LONGSUM, LONGDIFF, NORMALISE, SHIFTRIGHT, SHIFTLEFT — implemented as Go helper functions), CAUSEERROR (maps to `panic("CAUSEERROR")`).
 
 ## Course Module Testing
 

TODO.md

@@ -16,7 +16,7 @@
 ### Data Types & Declarations
 - **INT, INT16, INT32, INT64, BYTE, BOOL, REAL, REAL32, REAL64** — Scalar types (INT16/32/64 map to int16/32/64, REAL/REAL64 map to float64, REAL32 maps to float32)
 - **Variable declarations** — `INT x, y, z:`
-- **Arrays** — `[n]TYPE arr:` with index expressions; multi-dimensional `[n][m]TYPE` with nested init loops
+- **Arrays** — `[n]TYPE arr:` with index expressions; multi-dimensional `[n][m]TYPE` with nested init loops; mixed-dimension abbreviations `[][n]TYPE` and `[][]TYPE`
 - **Channels** — `CHAN OF TYPE c:` with send (`!`) and receive (`?`); `CHAN BYTE` shorthand (without `OF`)
 - **Channel arrays** — `[n]CHAN OF TYPE cs:` with indexed send/receive; multi-dimensional `[n][m]CHAN OF TYPE` with nested init loops; `[]CHAN`, `[][]CHAN`, etc. proc params
 - **Channel direction** — `CHAN OF INT c?` (receive-only) and `CHAN OF INT c!` (send-only); direction annotations at call sites (`out!`, `in?`) accepted and ignored

ast/ast.go

@@ -491,14 +491,13 @@ func (se *SliceExpr) TokenLiteral() string { return se.Token.Literal }
 
 // Abbreviation represents an abbreviation: VAL INT x IS 42:, INT y IS z:, or INITIAL INT x IS 42:
 type Abbreviation struct {
-	Token        lexer.Token // VAL, INITIAL, or type token
-	IsVal        bool        // true for VAL abbreviations
-	IsInitial    bool        // true for INITIAL declarations
-	IsOpenArray  bool        // true for []TYPE abbreviations (e.g. VAL []BYTE)
-	IsFixedArray bool        // true for [n]TYPE abbreviations (e.g. VAL [8]INT)
-	Type         string      // "INT", "BYTE", "BOOL", etc.
-	Name         string      // variable name
-	Value        Expression  // the expression
+	Token         lexer.Token // VAL, INITIAL, or type token
+	IsVal         bool        // true for VAL abbreviations
+	IsInitial     bool        // true for INITIAL declarations
+	OpenArrayDims int         // number of [] dimensions (1 for []BYTE, 2 for [][2]BYTE or [][]INT, etc.)
+	Type          string      // "INT", "BYTE", "BOOL", etc.
+	Name          string      // variable name
+	Value         Expression  // the expression
 }
 
 func (a *Abbreviation) statementNode()       {}

codegen/codegen.go

@@ -296,16 +296,18 @@ func (g *Generator) Generate(program *ast.Program) string {
 			g.write("\n")
 		} else {
 			goType := g.occamTypeToGo(abbr.Type)
-			if abbr.IsOpenArray || abbr.IsFixedArray {
-				goType = "[]" + goType
+			if abbr.OpenArrayDims > 0 {
+				goType = strings.Repeat("[]", abbr.OpenArrayDims) + goType
 			}
 			g.builder.WriteString("var ")
 			g.write(fmt.Sprintf("%s %s = ", goIdent(abbr.Name), goType))
 			// Wrap string literals with []byte() when assigned to []byte variables
-			if _, isStr := abbr.Value.(*ast.StringLiteral); isStr && abbr.IsOpenArray && abbr.Type == "BYTE" {
+			if _, isStr := abbr.Value.(*ast.StringLiteral); isStr && abbr.OpenArrayDims > 0 && abbr.Type == "BYTE" {
 				g.write("[]byte(")
 				g.generateExpression(abbr.Value)
 				g.write(")")
+			} else if al, isArr := abbr.Value.(*ast.ArrayLiteral); isArr && abbr.OpenArrayDims > 1 {
+				g.generateTypedArrayLiteral(al, goType)
 			} else {
 				g.generateExpression(abbr.Value)
 			}
@@ -1198,18 +1200,20 @@ func (g *Generator) generateAbbreviation(abbr *ast.Abbreviation) {
 	g.builder.WriteString(strings.Repeat("\t", g.indent))
 	if abbr.Type != "" {
 		goType := g.occamTypeToGo(abbr.Type)
-		if abbr.IsOpenArray || abbr.IsFixedArray {
-			goType = "[]" + goType
+		if abbr.OpenArrayDims > 0 {
+			goType = strings.Repeat("[]", abbr.OpenArrayDims) + goType
 		}
 		g.write(fmt.Sprintf("var %s %s = ", goIdent(abbr.Name), goType))
 	} else {
 		g.write(fmt.Sprintf("%s := ", goIdent(abbr.Name)))
 	}
 	// Wrap string literals with []byte() when assigned to []byte variables
-	if _, isStr := abbr.Value.(*ast.StringLiteral); isStr && abbr.IsOpenArray && abbr.Type == "BYTE" {
+	if _, isStr := abbr.Value.(*ast.StringLiteral); isStr && abbr.OpenArrayDims > 0 && abbr.Type == "BYTE" {
 		g.write("[]byte(")
 		g.generateExpression(abbr.Value)
 		g.write(")")
+	} else if al, isArr := abbr.Value.(*ast.ArrayLiteral); isArr && abbr.OpenArrayDims > 1 {
+		g.generateTypedArrayLiteral(al, strings.Repeat("[]", abbr.OpenArrayDims)+g.occamTypeToGo(abbr.Type))
 	} else {
 		g.generateExpression(abbr.Value)
 	}
@@ -2949,6 +2953,32 @@ func (g *Generator) generateArrayLiteral(al *ast.ArrayLiteral) {
 	g.write("}")
 }
 
+// generateTypedArrayLiteral emits a typed Go slice literal with the given Go type.
+// For nested arrays (e.g. [][]int), inner array literals use bare {e1, e2} syntax
+// (Go composite literal elision).
+func (g *Generator) generateTypedArrayLiteral(al *ast.ArrayLiteral, goType string) {
+	g.write(goType + "{")
+	for i, elem := range al.Elements {
+		if i > 0 {
+			g.write(", ")
+		}
+		if innerArr, ok := elem.(*ast.ArrayLiteral); ok {
+			// Inner array: use bare composite literal {e1, e2, ...}
+			g.write("{")
+			for j, inner := range innerArr.Elements {
+				if j > 0 {
+					g.write(", ")
+				}
+				g.generateExpression(inner)
+			}
+			g.write("}")
+		} else {
+			g.generateExpression(elem)
+		}
+	}
+	g.write("}")
+}
+
 // generateRetypesDecl emits code for a RETYPES declaration.
 // VAL INT X RETYPES X : — reinterpret float32/64 bits as int(s)
 // When source and target share the same name (shadowing a parameter), the parameter

codegen/e2e_array_test.go

@@ -405,3 +405,54 @@ SEQ
 		t.Errorf("expected %q, got %q", expected, output)
 	}
 }
+
+func TestE2E_MixedDimAbbreviation(t *testing.T) {
+	// [][2]INT abbreviation with nested array literals
+	occam := `SEQ
+  VAL [][2]INT pairs IS [[10, 20], [30, 40]]:
+  print.int(pairs[0][0])
+  print.int(pairs[0][1])
+  print.int(pairs[1][0])
+  print.int(pairs[1][1])
+`
+	output := transpileCompileRun(t, occam)
+	expected := "10\n20\n30\n40\n"
+	if output != expected {
+		t.Errorf("expected %q, got %q", expected, output)
+	}
+}
+
+func TestE2E_MixedDimProcParam(t *testing.T) {
+	// PROC with [][2]INT parameter
+	occam := `PROC print.pairs(VAL [][2]INT pairs)
+  SEQ i = 0 FOR SIZE pairs
+    SEQ
+      print.int(pairs[i][0])
+      print.int(pairs[i][1])
+:
+SEQ
+  VAL [][2]INT data IS [[10, 20], [30, 40], [50, 60]]:
+  print.pairs(data)
+`
+	output := transpileCompileRun(t, occam)
+	expected := "10\n20\n30\n40\n50\n60\n"
+	if output != expected {
+		t.Errorf("expected %q, got %q", expected, output)
+	}
+}
+
+func TestE2E_MultiDimOpenAbbreviation(t *testing.T) {
+	// [][]INT abbreviation
+	occam := `SEQ
+  VAL [][]INT matrix IS [[1, 2], [3, 4]]:
+  print.int(matrix[0][0])
+  print.int(matrix[0][1])
+  print.int(matrix[1][0])
+  print.int(matrix[1][1])
+`
+	output := transpileCompileRun(t, occam)
+	expected := "1\n2\n3\n4\n"
+	if output != expected {
+		t.Errorf("expected %q, got %q", expected, output)
+	}
+}

parser/parser.go

@@ -327,31 +327,33 @@ func (p *Parser) parseAbbreviation() ast.Statement {
 
 	p.nextToken()
 
-	// Check for []TYPE (open array abbreviation)
-	isOpenArray := false
-	if p.curTokenIs(lexer.LBRACKET) && p.peekTokenIs(lexer.RBRACKET) {
-		isOpenArray = true
-		p.nextToken() // consume ]
-		p.nextToken() // move to type
-	}
-
-	// Check for [n]TYPE (fixed-size array, used in RETYPES)
-	isArray := false
+	// Count bracket dimensions: [] (open) and [n] (fixed) in any combination
+	// e.g. []BYTE = 1 dim, [][2]BYTE = 2 dims, [][]INT = 2 dims, [8]INT = 1 dim (fixed, for RETYPES)
+	dims := 0
+	isFixedArray := false
 	var arraySize ast.Expression
-	if !isOpenArray && p.curTokenIs(lexer.LBRACKET) {
-		// Could be [n]TYPE name RETYPES ...
-		isArray = true
-		p.nextToken() // move past [
-		arraySize = p.parseExpression(LOWEST)
-		if !p.expectPeek(lexer.RBRACKET) {
-			return nil
+	for p.curTokenIs(lexer.LBRACKET) {
+		if p.peekTokenIs(lexer.RBRACKET) {
+			// Open dimension: []
+			dims++
+			p.nextToken() // consume ]
+			p.nextToken() // past ]
+		} else {
+			// Fixed dimension: [n]
+			dims++
+			isFixedArray = true
+			p.nextToken() // past [
+			arraySize = p.parseExpression(LOWEST)
+			if !p.expectPeek(lexer.RBRACKET) {
+				return nil
+			}
+			p.nextToken() // past ]
 		}
-		p.nextToken() // move to type
 	}
 
 	// Check for untyped VAL abbreviation: VAL name IS expr :
 	// Detect: curToken is IDENT and peekToken is IS (no type keyword)
-	if !isOpenArray && !isArray && p.curTokenIs(lexer.IDENT) && p.peekTokenIs(lexer.IS) {
+	if dims == 0 && p.curTokenIs(lexer.IDENT) && p.peekTokenIs(lexer.IS) {
 		name := p.curToken.Literal
 		p.nextToken() // consume IS
 		p.nextToken() // move to expression
@@ -395,7 +397,7 @@ func (p *Parser) parseAbbreviation() ast.Statement {
 			Token:      token,
 			IsVal:      true,
 			TargetType: typeName,
-			IsArray:    isArray,
+			IsArray:    isFixedArray,
 			ArraySize:  arraySize,
 			Name:       name,
 			Source:      source,
@@ -417,13 +419,12 @@ func (p *Parser) parseAbbreviation() ast.Statement {
 	}
 
 	return &ast.Abbreviation{
-		Token:        token,
-		IsVal:        true,
-		IsOpenArray:  isOpenArray,
-		IsFixedArray: isArray,
-		Type:         typeName,
-		Name:         name,
-		Value:        value,
+		Token:         token,
+		IsVal:         true,
+		OpenArrayDims: dims,
+		Type:          typeName,
+		Name:          name,
+		Value:         value,
 	}
 }
 
@@ -2150,7 +2151,8 @@ func (p *Parser) parseProcParams() []ast.ProcParam {
 			p.nextToken()
 		}
 
-		// Check for []...CHAN OF <type>, []...TYPE (open array), or [n]TYPE (fixed-size array)
+		// Check for []...CHAN OF <type>, []...TYPE (open array), [n]TYPE (fixed-size array),
+		// or mixed [][n]TYPE (open+fixed dimensions)
 		if p.curTokenIs(lexer.LBRACKET) {
 			if p.peekTokenIs(lexer.RBRACKET) {
 				// Open array: [][]...CHAN OF TYPE or [][]...TYPE
@@ -2161,6 +2163,16 @@ func (p *Parser) parseProcParams() []ast.ProcParam {
 					p.nextToken() // consume ]
 					p.nextToken() // move past ]
 				}
+				// After open [] pairs, check for trailing [n] fixed dims (e.g. [][2]TYPE)
+				for p.curTokenIs(lexer.LBRACKET) && !p.peekTokenIs(lexer.RBRACKET) {
+					dims++
+					p.nextToken() // past [
+					// skip size expression tokens until ]
+					for !p.curTokenIs(lexer.RBRACKET) && !p.curTokenIs(lexer.EOF) {
+						p.nextToken()
+					}
+					p.nextToken() // past ]
+				}
 				if p.curTokenIs(lexer.CHAN) {
 					// []...CHAN OF <type> or []...CHAN <type> (channel array parameter)
 					param.IsChan = true
@@ -2189,7 +2201,8 @@ func (p *Parser) parseProcParams() []ast.ProcParam {
 					return params
 				}
 			} else {
-				// Fixed-size array: [n]TYPE
+				// Fixed-size array: [n]TYPE — mapped to open array (slice) param
+				dims := 1
 				p.nextToken() // move past [
 				if !p.curTokenIs(lexer.INT) {
 					p.addError(fmt.Sprintf("expected array size, got %s", p.curToken.Type))
@@ -2199,7 +2212,17 @@ func (p *Parser) parseProcParams() []ast.ProcParam {
 				if !p.expectPeek(lexer.RBRACKET) {
 					return params
 				}
-				p.nextToken() // move to type
+				p.nextToken() // move past ]
+				// Check for additional [n] dims after the first (e.g. [3][4]TYPE)
+				for p.curTokenIs(lexer.LBRACKET) && !p.peekTokenIs(lexer.RBRACKET) {
+					dims++
+					p.nextToken() // past [
+					for !p.curTokenIs(lexer.RBRACKET) && !p.curTokenIs(lexer.EOF) {
+						p.nextToken()
+					}
+					p.nextToken() // past ]
+				}
+				_ = dims // ArraySize already set; dims only relevant for open arrays
 				if isTypeToken(p.curToken.Type) {
 					param.Type = p.curToken.Literal
 				} else if p.curTokenIs(lexer.IDENT) && p.recordNames[p.curToken.Literal] {