make variadics require at least 1 item, as that's most often what we need

Author: xrstf

pkg/builtin/core.go

@@ -34,19 +34,19 @@ func ifElseFunction(ctx types.Context, test bool, yes, no ast.Expression) (any,
 	return result, err
 }
 
-// (This signature ensures do is always called with 1 expression at least.)
-
-func doFunction(ctx types.Context, arg ast.Expression, args ...ast.Expression) (any, error) {
-	tupleCtx, result, err := eval.EvalExpression(ctx, arg)
-	if err != nil {
-		return nil, fmt.Errorf("argument #0: %w", err)
-	}
+// NB: Variadic functions always require at least 1 argument in Rudi to match.
+func doFunction(ctx types.Context, args ...ast.Expression) (any, error) {
+	var (
+		tupleCtx = ctx
+		result   any
+		err      error
+	)
 
 	// do not use evalArgs(), as we want to inherit the context between expressions
-	for i, arg := range args {
+	for _, arg := range args {
 		tupleCtx, result, err = eval.EvalExpression(tupleCtx, arg)
 		if err != nil {
-			return nil, fmt.Errorf("argument #%d: %w", i+1, err)
+			return nil, err
 		}
 	}
 
@@ -121,28 +121,23 @@ func hasFunction(ctx types.Context, arg ast.Expression) (any, error) {
 }
 
 // (default TEST:Expression FALLBACK:any)
-func defaultFunction(ctx types.Context, test ast.Expression, fallback ast.Expression) (any, error) {
-	_, result, err := eval.EvalExpression(ctx, test)
-	if err != nil {
-		return nil, fmt.Errorf("argument #0: %w", err)
-	}
-
-	// this function purposefully always uses humane coalescing for this check
-	boolified, err := coalescing.NewHumane().ToBool(result)
+func defaultFunction(ctx types.Context, value any, fallback ast.Expression) (any, error) {
+	// this function purposefully always uses humane coalescing, but only for this check
+	boolified, err := coalescing.NewHumane().ToBool(value)
 	if err != nil {
 		return nil, fmt.Errorf("argument #0: %w", err)
 	}
 
 	if boolified {
-		return result, nil
+		return value, nil
 	}
 
-	_, result, err = eval.EvalExpression(ctx, fallback)
+	_, value, err = eval.EvalExpression(ctx, fallback)
 	if err != nil {
 		return nil, fmt.Errorf("argument #1: %w", err)
 	}
 
-	return result, nil
+	return value, nil
 }
 
 func tryFunction(ctx types.Context, test ast.Expression) (any, error) {
@@ -283,6 +278,10 @@ func isEmptyFunction(val bool) (any, error) {
 	return !val, nil
 }
 
-func errorFunction(ctx types.Context, format string, args ...any) (any, error) {
+func errorFunction(message string) (any, error) {
+	return nil, errors.New(message)
+}
+
+func fmtErrorFunction(format string, args ...any) (any, error) {
 	return nil, fmt.Errorf(format, args...)
 }

pkg/builtin/functions.go

@@ -19,7 +19,7 @@ var (
 		"delete":  functions.NewBuilder(deleteFunction).WithBangHandler(deleteBangHandler).WithDescription("removes a key from an object or an item from a vector").Build(),
 		"do":      functions.NewBuilder(doFunction).WithDescription("eval a sequence of statements where only one expression is valid").Build(),
 		"empty?":  functions.NewBuilder(isEmptyFunction).WithCoalescer(humaneCoalescer).WithDescription("returns true when the given value is empty-ish (0, false, null, \"\", ...)").Build(),
-		"error":   functions.NewBuilder(errorFunction).WithDescription("returns an error").Build(),
+		"error":   functions.NewBuilder(errorFunction, fmtErrorFunction).WithDescription("returns an error").Build(),
 		"has?":    functions.NewBuilder(hasFunction).WithDescription("returns true if the given symbol's path expression points to an existing value").Build(),
 		"if":      functions.NewBuilder(ifElseFunction, ifFunction).WithDescription("evaluate one of two expressions based on a condition").Build(),
 		"set":     functions.NewBuilder(setFunction).WithDescription("set a value in a variable/document, only really useful with ! modifier (set!)").Build(),

pkg/builtin/lists.go

@@ -25,6 +25,7 @@ func stringLenFunction(s string) (any, error) {
 	return len(s), nil
 }
 
+// (append VEC ITEMS+)
 func appendToVectorFunction(base []any, args ...any) (any, error) {
 	result := []any{}
 	result = append(result, base...)
@@ -33,18 +34,22 @@ func appendToVectorFunction(base []any, args ...any) (any, error) {
 	return result, nil
 }
 
+// (append STR ITEMS+)
 func appendToStringFunction(base string, args ...string) (any, error) {
 	return base + strings.Join(args, ""), nil
 }
 
+// (prepend VEC ITEMS+)
 func prependToVectorFunction(base []any, args ...any) (any, error) {
 	return append(args, base...), nil
 }
 
+// (prepend STR ITEMS+)
 func prependToStringFunction(base string, args ...string) (any, error) {
 	return strings.Join(args, "") + base, nil
 }
 
+// (reverse STR)
 func reverseStringFunction(s string) (any, error) {
 	// thank you https://stackoverflow.com/a/10030772
 	result := []rune(s)
@@ -55,6 +60,7 @@ func reverseStringFunction(s string) (any, error) {
 	return string(result), nil
 }
 
+// (reverse VEC)
 func reverseVectorFunction(vec []any) (any, error) {
 	// clone original data
 	result := append([]any{}, vec...)
@@ -409,10 +415,12 @@ func decodeNamingVector(expr ast.Expression) (indexName string, valueName string
 	return indexName, valueName, nil
 }
 
+// (contains? STR STR)
 func stringContainsFunction(haystack string, needle string) (any, error) {
 	return strings.Contains(haystack, needle), nil
 }
 
+// (contains? VEC ITEM)
 func vectorContainsFunction(ctx types.Context, haystack []any, needle any) (any, error) {
 	for _, val := range haystack {
 		equal, err := equality.Equal(ctx.Coalesce(), val, needle)

pkg/builtin/logic.go

@@ -11,11 +11,7 @@ import (
 	"go.xrstf.de/rudi/pkg/lang/ast"
 )
 
-func andFunction(ctx types.Context, base bool, args ...ast.Expression) (any, error) {
-	if !base {
-		return false, nil
-	}
-
+func andFunction(ctx types.Context, args ...ast.Expression) (any, error) {
 	for i, arg := range args {
 		_, evaluated, err := eval.EvalExpression(ctx, arg)
 		if err != nil {
@@ -35,11 +31,7 @@ func andFunction(ctx types.Context, base bool, args ...ast.Expression) (any, err
 	return true, nil
 }
 
-func orFunction(ctx types.Context, base bool, args ...ast.Expression) (any, error) {
-	if base {
-		return true, nil
-	}
-
+func orFunction(ctx types.Context, args ...ast.Expression) (any, error) {
 	for i, arg := range args {
 		_, evaluated, err := eval.EvalExpression(ctx, arg)
 		if err != nil {

pkg/builtin/math.go

@@ -9,84 +9,71 @@ import (
 	"go.xrstf.de/rudi/pkg/lang/ast"
 )
 
-func integerAddFunction(a, b int64, extra ...int64) (any, error) {
-	sum := a + b
+func integerAddFunction(base int64, extra ...int64) (any, error) {
 	for _, num := range extra {
-		sum += num
+		base += num
 	}
 
-	return sum, nil
+	return base, nil
 }
 
-func numberAddFunction(a, b ast.Number, extra ...ast.Number) (any, error) {
-	sum := a.MustToFloat() + b.MustToFloat()
+func numberAddFunction(base ast.Number, extra ...ast.Number) (any, error) {
+	sum := base.MustToFloat()
 	for _, num := range extra {
 		sum += num.MustToFloat()
 	}
 
 	return sum, nil
 }
 
-func integerSubFunction(a, b int64, extra ...int64) (any, error) {
-	diff := a - b
+func integerSubFunction(base int64, extra ...int64) (any, error) {
 	for _, num := range extra {
-		diff -= num
+		base -= num
 	}
 
-	return diff, nil
+	return base, nil
 }
 
-func numberSubFunction(a, b ast.Number, extra ...ast.Number) (any, error) {
-	diff := a.MustToFloat() - b.MustToFloat()
+func numberSubFunction(base ast.Number, extra ...ast.Number) (any, error) {
+	diff := base.MustToFloat()
 	for _, num := range extra {
 		diff -= num.MustToFloat()
 	}
 
 	return diff, nil
 }
 
-func integerMultFunction(a, b int64, extra ...int64) (any, error) {
-	product := a * b
+func integerMultFunction(base int64, extra ...int64) (any, error) {
 	for _, num := range extra {
-		product *= num
+		base *= num
 	}
 
-	return product, nil
+	return base, nil
 }
 
-func numberMultFunction(a, b ast.Number, extra ...ast.Number) (any, error) {
-	product := a.MustToFloat() * b.MustToFloat()
+func numberMultFunction(base ast.Number, extra ...ast.Number) (any, error) {
+	product := base.MustToFloat()
 	for _, num := range extra {
 		product *= num.MustToFloat()
 	}
 
 	return product, nil
 }
 
-func integerDivFunction(a, b int64, extra ...int64) (any, error) {
-	if b == 0 {
-		return nil, errors.New("division by zero")
-	}
-
-	result := a / b
-
+func integerDivFunction(base int64, extra ...int64) (any, error) {
 	for _, num := range extra {
 		if num == 0 {
 			return nil, errors.New("division by zero")
 		}
 
-		result /= num
+		base /= num
 	}
 
-	return result, nil
+	return base, nil
 }
 
-func numberDivFunction(a, b ast.Number, extra ...ast.Number) (any, error) {
-	if b.MustToFloat() == 0 {
-		return nil, errors.New("division by zero")
-	}
-
-	result := a.MustToFloat() / b.MustToFloat()
+func numberDivFunction(base ast.Number, extra ...ast.Number) (any, error) {
+	result := base.MustToFloat()
 
 	for _, num := range extra {
 		if num.MustToFloat() == 0 {

pkg/eval/functions/args_consumer.go

@@ -222,8 +222,16 @@ func contextConsumer(ctx types.Context, args []cachedExpression) (asserted []any
 	return []any{ctx}, args, nil
 }
 
+// toVariadicConsumer wraps a singular consumer to consume all remaining args. In constrast to
+// Go, variadic arguments must have at least 1 item (i.e. calling func(foo string, a ...int) with
+// ("abc") only is invalid).
 func toVariadicConsumer(singleConsumer argsConsumer) argsConsumer {
 	return func(ctx types.Context, args []cachedExpression) (asserted []any, remaining []cachedExpression, err error) {
+		// at least one argument is required, otherwise variadics do not match
+		if len(args) == 0 {
+			return nil, nil, nil
+		}
+
 		leftover := args
 		result := []any{}
 

pkg/eval/functions/args_consumer_test.go

@@ -221,3 +221,33 @@ func TestExpressionConsumer(t *testing.T) {
 		})
 	}
 }
+
+func TestVariadicConsumer(t *testing.T) {
+	testcases := []argsConsumerTestcase{
+		{
+			name:      "variadic request at least 1 item",
+			args:      []ast.Expression{},
+			expected:  nil,
+			remaining: 0,
+		},
+		{
+			name: "consume all strings",
+			args: []ast.Expression{
+				ast.String("foo"),
+				ast.Bool(true),
+				ast.Null{},
+			},
+			expected:  []any{"foo", "true", ""},
+			remaining: 0,
+		},
+	}
+
+	coalescer := coalescing.NewHumane()
+	ctx := types.NewContext(types.Document{}, nil, nil, coalescer)
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			tc.Test(t, ctx, toVariadicConsumer(stringConsumer))
+		})
+	}
+}

pkg/eval/functions/args_matcher_test.go

@@ -216,6 +216,10 @@ func TestNewArgsMatcherSignatures(t *testing.T) {
 			fun:     func(map[string][]any) (any, error) { panic("") },
 			invalid: true,
 		},
+		{
+			name: "accept only variadic arg",
+			fun:  func(...int64) (any, error) { panic("") },
+		},
 		{
 			name: "accept variadic basic arg",
 			fun:  func(string, []any, ...int64) (any, error) { panic("") },
@@ -332,11 +336,10 @@ func TestArgsMatcher(t *testing.T) {
 			expected: []any{ast.Shim{Value: 1}},
 		},
 		{
-			name:     "basic variadic parameter with no args",
-			fun:      func(...string) (any, error) { return nil, nil },
-			args:     []ast.Expression{},
-			match:    true,
-			expected: []any{},
+			name:  "variadic parameters require at least 1 item",
+			fun:   func(...string) (any, error) { return nil, nil },
+			args:  []ast.Expression{},
+			match: false,
 		},
 		{
 			name:     "basic variadic parameter",
@@ -353,11 +356,10 @@ func TestArgsMatcher(t *testing.T) {
 			expected: []any{"foo", "bar"},
 		},
 		{
-			name:     "variadic can be empty",
-			fun:      func(string, ...string) (any, error) { return nil, nil },
-			args:     []ast.Expression{ast.String("foo")},
-			match:    true,
-			expected: []any{"foo"},
+			name:  "variadic cannot be empty",
+			fun:   func(string, ...string) (any, error) { return nil, nil },
+			args:  []ast.Expression{ast.String("foo")},
+			match: false,
 		},
 		{
 			name: "variadic slices",