Performance and style fixes (#1981)

* Switch to integer ranges in for loops

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Switch to slices functions where appropriate

A number of utility functions can be replaced outright; since Miller
can technically be used as a library, these are deprecated rather than
removed. go:fix directives ensure that they can be replaced
automatically.

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Switch to reflect.TypeFor

This is slightly more efficient than TypeOf when the type is known at
compile time.

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Switch to strings.SplitSeq instead of strings.Split

SplitSeq results in fewer allocations.

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Drop obsolete build directives

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Use min/max instead of explicit comparisons

Signed-off-by: Stephen Kitt <steve@sk2.org>

* Append slices instead of looping

Signed-off-by: Stephen Kitt <steve@sk2.org>

---------

Signed-off-by: Stephen Kitt <steve@sk2.org>

pkg/auxents/hex.go

@@ -108,7 +108,7 @@ func hexDumpFile(istream *os.File, doRaw bool) {
 		}
 
 		// Print hex payload
-		for i := 0; i < bufferSize; i++ {
+		for i := range bufferSize {
 			if i < numBytesRead {
 				fmt.Printf("%02x ", buffer[i])
 			} else {
@@ -125,7 +125,7 @@ func hexDumpFile(istream *os.File, doRaw bool) {
 		if !doRaw {
 			fmt.Printf("|")
 
-			for i := 0; i < numBytesRead; i++ {
+			for i := range numBytesRead {
 				if buffer[i] >= 0x20 && buffer[i] <= 0x7e {
 					fmt.Printf("%c", buffer[i])
 				} else {

pkg/bifs/stats.go

@@ -458,7 +458,7 @@ func BIF_sort_collection(collection *mlrval.Mlrval) *mlrval.Mlrval {
 		arrayval := collection.AcquireArrayValue()
 		n := len(arrayval)
 		array = make([]*mlrval.Mlrval, n)
-		for i := 0; i < n; i++ {
+		for i := range n {
 			array[i] = arrayval[i].Copy()
 		}
 	} else {

pkg/bifs/stats_test.go

@@ -11,7 +11,7 @@ import (
 
 func stats_test_array(n int) *mlrval.Mlrval {
 	a := make([]*mlrval.Mlrval, n)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		a[i] = mlrval.FromInt(int64(i))
 	}
 	return mlrval.FromArray(a)
@@ -20,7 +20,7 @@ func stats_test_array(n int) *mlrval.Mlrval {
 func array_to_map_for_test(a *mlrval.Mlrval) *mlrval.Mlrval {
 	array := a.AcquireArrayValue()
 	m := mlrval.NewMlrmap()
-	for i := 0; i < len(array); i++ {
+	for i := range array {
 		key := fmt.Sprint(i)
 		val := array[i]
 		m.PutCopy(key, val)
@@ -34,7 +34,7 @@ func TestBIF_count(t *testing.T) {
 	output := BIF_count(input)
 	assert.True(t, output.IsError())
 
-	for n := 0; n < 5; n++ {
+	for n := range 5 {
 		input = stats_test_array(n)
 		assert.True(t, mlrval.Equals(BIF_count(input), mlrval.FromInt(int64(n))))
 

pkg/cli/flag_types.go

@@ -37,6 +37,7 @@ package cli
 
 import (
 	"fmt"
+	"slices"
 	"sort"
 	"strings"
 
@@ -390,12 +391,7 @@ func (flag *Flag) Owns(input string) bool {
 	if flag.name == input {
 		return true
 	}
-	for _, name := range flag.altNames {
-		if name == input {
-			return true
-		}
-	}
-	return false
+	return slices.Contains(flag.altNames, input)
 }
 
 // Matches is like Owns but is for substring matching, for on-line help with

pkg/dsl/ast_print.go

@@ -57,7 +57,7 @@ func (node *ASTNode) Print() {
 // printAux is a recursion-helper for Print.
 func (node *ASTNode) printAux(depth int) {
 	// Indent
-	for i := 0; i < depth; i++ {
+	for range depth {
 		fmt.Print("    ")
 	}
 
@@ -83,14 +83,14 @@ func (node *ASTNode) PrintParex() {
 // printParexAux is a recursion-helper for PrintParex.
 func (node *ASTNode) printParexAux(depth int) {
 	if node.IsLeaf() {
-		for i := 0; i < depth; i++ {
+		for range depth {
 			fmt.Print("    ")
 		}
 		fmt.Println(node.Text())
 
 	} else if node.ChildrenAreAllLeaves() {
 		// E.g. (= sum 0) or (+ 1 2)
-		for i := 0; i < depth; i++ {
+		for range depth {
 			fmt.Print("    ")
 		}
 		fmt.Print("(")
@@ -104,7 +104,7 @@ func (node *ASTNode) printParexAux(depth int) {
 
 	} else {
 		// Parent and opening parenthesis on first line
-		for i := 0; i < depth; i++ {
+		for range depth {
 			fmt.Print("    ")
 		}
 		fmt.Print("(")
@@ -116,7 +116,7 @@ func (node *ASTNode) printParexAux(depth int) {
 		}
 
 		// Closing parenthesis on last line
-		for i := 0; i < depth; i++ {
+		for range depth {
 			fmt.Print("    ")
 		}
 		fmt.Println(")")

pkg/dsl/cst/hofs.go

@@ -695,7 +695,7 @@ func sortM(
 
 	// Make a new map with entries in the new sort order.
 	outmap := mlrval.NewMlrmap()
-	for i := int64(0); i < n; i++ {
+	for i := range n {
 		entry := entries[i]
 		outmap.PutCopy(entry.Key, entry.Value)
 	}

pkg/input/record_reader_csv.go

@@ -229,7 +229,7 @@ func (reader *RecordReaderCSV) getRecordBatch(
 		if reader.header == nil { // implicit CSV header
 			n := len(csvRecord)
 			reader.header = make([]string, n)
-			for i := 0; i < n; i++ {
+			for i := range n {
 				reader.header[i] = strconv.Itoa(i + 1)
 			}
 		}
@@ -240,7 +240,7 @@ func (reader *RecordReaderCSV) getRecordBatch(
 		nd := int64(len(csvRecord))
 
 		if nh == nd {
-			for i := int64(0); i < nh; i++ {
+			for i := range nh {
 				key := reader.header[i]
 				value := mlrval.FromDeferredType(csvRecord[i])
 				_, err := record.PutReferenceMaybeDedupe(key, value, dedupeFieldNames)

pkg/input/record_reader_csvlite.go

@@ -332,7 +332,7 @@ func getRecordBatchImplicitCSVHeader(
 		if reader.headerStrings == nil {
 			n := len(fields)
 			reader.headerStrings = make([]string, n)
-			for i := 0; i < n; i++ {
+			for i := range n {
 				reader.headerStrings[i] = strconv.Itoa(i + 1)
 			}
 		} else {

pkg/input/record_reader_json.go

@@ -283,7 +283,7 @@ func (bsr *JSONCommentEnabledReader) populateFromLine(p []byte) int {
 		numBytesWritten = len(bsr.lineBytes)
 		bsr.lineBytes = nil
 	} else {
-		for i := 0; i < len(p); i++ {
+		for i := range p {
 			p[i] = bsr.lineBytes[i]
 		}
 		numBytesWritten = len(p)

pkg/input/record_reader_pprint.go

@@ -367,7 +367,7 @@ func getRecordBatchImplicitPprintHeader(
 		if reader.headerStrings == nil {
 			n := len(fields)
 			reader.headerStrings = make([]string, n)
-			for i := 0; i < n; i++ {
+			for i := range n {
 				reader.headerStrings[i] = strconv.Itoa(i + 1)
 			}
 		} else {

pkg/input/record_reader_tsv.go

@@ -297,7 +297,7 @@ func getRecordBatchImplicitTSVHeader(
 		if reader.headerStrings == nil {
 			n := len(fields)
 			reader.headerStrings = make([]string, n)
-			for i := 0; i < n; i++ {
+			for i := range n {
 				reader.headerStrings[i] = strconv.Itoa(i + 1)
 			}
 		} else {

pkg/lib/mlrmath.go

@@ -117,7 +117,7 @@ func GetRealSymmetricEigensystem(
 	n := 2
 
 	found := false
-	for iter := 0; iter < JACOBI_MAXITER; iter++ {
+	for range JACOBI_MAXITER {
 		sum := 0.0
 		for i := 1; i < n; i++ {
 			for j := 0; j < i; j++ {
@@ -129,7 +129,7 @@ func GetRealSymmetricEigensystem(
 			break
 		}
 
-		for p := 0; p < n; p++ {
+		for p := range n {
 			for q := p + 1; q < n; q++ {
 				numer := L[p][p] - L[q][q]
 				denom := L[p][q] + L[q][p]
@@ -145,8 +145,8 @@ func GetRealSymmetricEigensystem(
 				c := 1.0 / math.Sqrt(t*t+1)
 				s := t * c
 
-				for pi := 0; pi < n; pi++ {
-					for pj := 0; pj < n; pj++ {
+				for pi := range n {
+					for pj := range n {
 						if pi == pj {
 							P[pi][pj] = 1.0
 						} else {
@@ -205,18 +205,18 @@ func matmul2(
 ) {
 	var T [2][2]float64
 	n := 2
-	for i := 0; i < n; i++ {
-		for j := 0; j < n; j++ {
+	for i := range n {
+		for j := range n {
 			sum := 0.0
-			for k := 0; k < n; k++ {
+			for k := range n {
 				sum += A[i][k] * B[k][j]
 			}
 			T[i][j] = sum
 		}
 	}
 	// Needs copy in case C's memory is the same as A and/or B
-	for i := 0; i < n; i++ {
-		for j := 0; j < n; j++ {
+	for i := range n {
+		for j := range n {
 			C[i][j] = T[i][j]
 		}
 	}
@@ -230,18 +230,18 @@ func matmul2t(
 ) {
 	var T [2][2]float64
 	n := 2
-	for i := 0; i < n; i++ {
-		for j := 0; j < n; j++ {
+	for i := range n {
+		for j := range n {
 			sum := 0.0
-			for k := 0; k < n; k++ {
+			for k := range n {
 				sum += A[k][i] * B[k][j]
 			}
 			T[i][j] = sum
 		}
 	}
 	// Needs copy in case C's memory is the same as A and/or B
-	for i := 0; i < n; i++ {
-		for j := 0; j < n; j++ {
+	for i := range n {
+		for j := range n {
 			C[i][j] = T[i][j]
 		}
 	}
@@ -353,7 +353,7 @@ func logisticRegressionAux(
 		d2ldb2 := 0.0
 		ell0 := 0.0
 
-		for i := 0; i < n; i++ {
+		for i := range n {
 			xi := xs[i]
 			yi := ys[i]
 			pi := lrp(xi, m0, b0)
@@ -391,7 +391,7 @@ func logisticRegressionAux(
 		b = b0 - Hinvgradb
 
 		ell := 0.0
-		for i := 0; i < n; i++ {
+		for i := range n {
 			xi := xs[i]
 			yi := ys[i]
 			qi := lrq(xi, m, b)

pkg/lib/util.go

@@ -3,6 +3,7 @@ package lib
 import (
 	"fmt"
 	"os"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -49,35 +50,29 @@ func StringListToSet(stringList []string) map[string]bool {
 	return stringSet
 }
 
+// SortStrings sorts strs in place.
+//
+// Deprecated: use slices.Sort instead.
+//
+//go:fix inline
 func SortStrings(strs []string) {
-	// Go sort API: for ascending sort, return true if element i < element j.
-	sort.Slice(strs, func(i, j int) bool {
-		return strs[i] < strs[j]
-	})
+	slices.Sort(strs)
 }
 
+// ReverseStringList reverses strs in place.
+//
+// Deprecated: use slices.Reverse instead.
+//
+//go:fix inline
 func ReverseStringList(strs []string) {
-	n := len(strs)
-	i := 0
-	j := n - 1
-	for i < j {
-		temp := strs[i]
-		strs[i] = strs[j]
-		strs[j] = temp
-		i++
-		j--
-	}
+	slices.Reverse(strs)
 }
 
+// SortedStrings returns a new slice containing the strings in strs in ascending order.
 func SortedStrings(strs []string) []string {
 	result := make([]string, len(strs))
-	for i, s := range strs {
-		result[i] = s
-	}
-	// Go sort API: for ascending sort, return true if element i < element j.
-	sort.Slice(result, func(i, j int) bool {
-		return result[i] < result[j]
-	})
+	copy(result, strs)
+	slices.Sort(result)
 	return result
 }
 
@@ -202,13 +197,13 @@ func WriteTempFileOrDie(contents string) string {
 	return handle.Name()
 }
 
+// CopyStringArray returns a copy of input.
+//
+// Deprecated: use slices.Clone instead.
+//
+//go:fix inline
 func CopyStringArray(input []string) []string {
-	if input == nil {
-		return nil
-	}
-	output := make([]string, len(input))
-	copy(output, input)
-	return output
+	return slices.Clone(input)
 }
 
 func StripEmpties(input []string) []string {

pkg/mlrval/mlrmap_accessors.go

@@ -3,6 +3,7 @@ package mlrval
 import (
 	"bytes"
 	"fmt"
+	"slices"
 	"strconv"
 
 	"github.com/johnkerl/miller/v6/pkg/lib"
@@ -751,7 +752,7 @@ func (mlrmap *Mlrmap) Label(newNames []string) {
 func (mlrmap *Mlrmap) SortByKey() {
 	keys := mlrmap.GetKeys()
 
-	lib.SortStrings(keys)
+	slices.Sort(keys)
 
 	other := NewMlrmapAsRecord()
 
@@ -766,7 +767,7 @@ func (mlrmap *Mlrmap) SortByKey() {
 func (mlrmap *Mlrmap) SortByKeyRecursively() {
 	keys := mlrmap.GetKeys()
 
-	lib.SortStrings(keys)
+	slices.Sort(keys)
 
 	other := NewMlrmapAsRecord()
 

pkg/mlrval/mlrmap_json.go

@@ -71,7 +71,7 @@ func (mlrmap *Mlrmap) marshalJSONAuxMultiline(
 	for pe := mlrmap.Head; pe != nil; pe = pe.Next {
 		// Write the key which is necessarily string-valued in Miller, and in
 		// JSON for that matter :)
-		for i := 0; i < elementNestingDepth; i++ {
+		for range elementNestingDepth {
 			buffer.WriteString(JSON_INDENT_STRING)
 		}
 		encoded := string(millerJSONEncodeString(pe.Key))

pkg/mlrval/mlrval_json.go

@@ -491,7 +491,7 @@ func (mv *Mlrval) marshalJSONArrayMultipleLines(
 		if err != nil {
 			return "", err
 		}
-		for i := 0; i < elementNestingDepth; i++ {
+		for range elementNestingDepth {
 			buffer.WriteString(JSON_INDENT_STRING)
 		}
 		buffer.WriteString(elementString)

pkg/mlrval/mlrval_output.go

@@ -133,9 +133,9 @@ func (mv *Mlrval) StringifyValuesRecursively() {
 }
 
 func (mv *Mlrval) ShowSizes() {
-	fmt.Printf("TOTAL            %p %d\n", mv, reflect.TypeOf(*mv).Size())
+	fmt.Printf("TOTAL            %p %d\n", mv, reflect.TypeFor[Mlrval]().Size())
 	//fmt.Printf("mv.intf          %p %d\n", &mv.intf, reflect.TypeOf(mv.intf).Size())
-	fmt.Printf("mv.printrep      %p %d\n", &mv.printrep, reflect.TypeOf(mv.printrep).Size())
-	fmt.Printf("mv.printrepValid %p %d\n", &mv.printrepValid, reflect.TypeOf(mv.printrepValid).Size())
-	fmt.Printf("mv.mvtype        %p %d\n", &mv.mvtype, reflect.TypeOf(mv.mvtype).Size())
+	fmt.Printf("mv.printrep      %p %d\n", &mv.printrep, reflect.TypeFor[string]().Size())
+	fmt.Printf("mv.printrepValid %p %d\n", &mv.printrepValid, reflect.TypeFor[bool]().Size())
+	fmt.Printf("mv.mvtype        %p %d\n", &mv.mvtype, reflect.TypeFor[MVType]().Size())
 }

pkg/output/record_writer_pprint.go

@@ -339,7 +339,7 @@ func (writer *RecordWriterPPRINT) writePadding(
 	textWidth := utf8.RuneCountInString(text)
 	padWidth := fieldWidth - textWidth
 	ofs := writer.writerOptions.OFS
-	for i := 0; i < padWidth; i++ {
+	for range padWidth {
 		bufferedOutputStream.WriteString(ofs)
 	}
 }

pkg/parsing/errors/errors.go

@@ -11,6 +11,7 @@ package errors
 
 import (
 	"fmt"
+	"slices"
 	"strings"
 
 	"github.com/johnkerl/miller/v6/pkg/parsing/token"
@@ -60,13 +61,7 @@ func (e *Error) Error() string {
 	if e.Err != nil {
 		fmt.Fprintf(w, "%+v\n", e.Err)
 	} else {
-		suggestSemicolons := false
-		for _, expected := range e.ExpectedTokens {
-			if expected == ";" {
-				suggestSemicolons = true
-				break
-			}
-		}
+		suggestSemicolons := slices.Contains(e.ExpectedTokens, ";")
 
 		if suggestSemicolons {
 			fmt.Fprintf(w, "Please check for missing semicolon.\n")

pkg/pbnjay-strptime/strptime.go

@@ -90,8 +90,8 @@ func ParseLocation(value, format string, location *time.Location) (time.Time, er
 func Check(format string) error {
 	format = expandShorthands(format)
 
-	parts := strings.Split(format, "%")
-	for _, ps := range parts {
+	parts := strings.SplitSeq(format, "%")
+	for ps := range parts {
 		// Since we split on '%', this is the format code
 
 		// This is for "%%"
@@ -289,11 +289,7 @@ func strptime_tz(
 						return time.Time{}, ErrFormatMismatch
 					}
 					// Allow single-digit at end of string (e.g. "1989-1-2" for %Y-%m-%d); we zero-pad when building.
-					if want > remaining {
-						sil = remaining
-					} else {
-						sil = want
-					}
+					sil = min(want, remaining)
 				}
 			}
 

pkg/platform/diff_notwindows.go

@@ -1,7 +1,6 @@
 // Handling diff or fc for regression-test.
 
 //go:build !windows
-// +build !windows
 
 package platform
 

pkg/platform/diff_windows.go

@@ -1,7 +1,6 @@
 // Handling diff or fc for regression-test.
 
 //go:build windows
-// +build windows
 
 package platform
 

pkg/platform/getargs_notwindows.go

@@ -2,7 +2,6 @@
 // particular care is taken, which is what this file does.
 
 //go:build !windows
-// +build !windows
 
 package platform
 

pkg/platform/getargs_windows.go

@@ -2,7 +2,6 @@
 // particular care is taken, which is what this file does.
 
 //go:build windows
-// +build windows
 
 package platform
 

pkg/platform/shellrun_notwindows.go

@@ -1,7 +1,6 @@
 // Wraps 'sh -c foo bar' or 'cmd /c foo bar', nominally for regression-testing.
 
 //go:build !windows
-// +build !windows
 
 package platform
 

pkg/platform/shellrun_windows.go

@@ -1,7 +1,6 @@
 // Wraps 'sh -c foo bar' or 'cmd /c foo bar', nominally for regression-testing.
 
 //go:build windows
-// +build windows
 
 package platform
 

pkg/platform/terminal_notwindows.go

@@ -1,5 +1,4 @@
 //go:build !windows
-// +build !windows
 
 package platform
 

pkg/platform/terminal_windows.go

@@ -1,5 +1,4 @@
 //go:build windows
-// +build windows
 
 package platform
 

pkg/runtime/state.go

@@ -5,6 +5,8 @@
 package runtime
 
 import (
+	"slices"
+
 	"github.com/johnkerl/miller/v6/pkg/cli"
 	"github.com/johnkerl/miller/v6/pkg/lib"
 	"github.com/johnkerl/miller/v6/pkg/mlrval"
@@ -78,12 +80,11 @@ func (state *State) Update(
 func (state *State) SetRegexCaptures(
 	captures []string,
 ) {
-	state.regexCapturesByFrame[0] = lib.CopyStringArray(captures)
+	state.regexCapturesByFrame[0] = slices.Clone(captures)
 }
 
 func (state *State) GetRegexCaptures() []string {
-	regexCaptures := state.regexCapturesByFrame[0]
-	return lib.CopyStringArray(regexCaptures)
+	return slices.Clone(state.regexCapturesByFrame[0])
 }
 
 func (state *State) PushRegexCapturesFrame() {

pkg/scan/digits_test.go

@@ -8,7 +8,7 @@ import (
 
 func TestIsDecimalDigit(t *testing.T) {
 	var c byte
-	for c = 0x00; c < 0xff; c++ {
+	for c = range byte(0xff) {
 		if c >= '0' && c <= '9' {
 			assert.True(t, isDecimalDigit(c))
 		} else {
@@ -19,7 +19,7 @@ func TestIsDecimalDigit(t *testing.T) {
 
 func TestIsOctalDigit(t *testing.T) {
 	var c byte
-	for c = 0x00; c < 0xff; c++ {
+	for c = range byte(0xff) {
 		if c >= '0' && c <= '7' {
 			assert.True(t, isOctalDigit(c))
 		} else {
@@ -30,7 +30,7 @@ func TestIsOctalDigit(t *testing.T) {
 
 func TestIsHexDigit(t *testing.T) {
 	var c byte
-	for c = 0x00; c < 0xff; c++ {
+	for c = range byte(0xff) {
 		if c >= '0' && c <= '9' {
 			assert.True(t, isHexDigit(c))
 		} else if c >= 'a' && c <= 'f' {
@@ -45,7 +45,7 @@ func TestIsHexDigit(t *testing.T) {
 
 func TestIsFloatDigit(t *testing.T) {
 	var c byte
-	for c = 0x00; c < 0xff; c++ {
+	for c = range byte(0xff) {
 		if c >= '0' && c <= '9' {
 			assert.True(t, isFloatDigit(c))
 		} else if c == '.' || c == '-' || c == '+' || c == 'e' || c == 'E' {

pkg/terminals/regtest/regtester.go

@@ -831,8 +831,8 @@ func (rt *RegTester) loadEnvFile(
 	}
 
 	keyValuePairs := lib.NewOrderedMap[string]()
-	lines := strings.Split(contents, "\n")
-	for _, line := range lines {
+	lines := strings.SplitSeq(contents, "\n")
+	for line := range lines {
 		line = strings.TrimSuffix(line, "\r")
 		if line == "" {
 			continue
@@ -868,8 +868,8 @@ func (rt *RegTester) loadStringPairFile(
 	}
 
 	pairs = []stringPair{}
-	lines := strings.Split(contents, "\n")
-	for _, line := range lines {
+	lines := strings.SplitSeq(contents, "\n")
+	for line := range lines {
 		line = strings.TrimSuffix(line, "\r")
 		if line == "" {
 			continue

pkg/terminals/repl/verbs.go

@@ -5,6 +5,7 @@ package repl
 import (
 	"fmt"
 	"os"
+	"slices"
 	"strings"
 
 	"github.com/johnkerl/miller/v6/pkg/colorizer"
@@ -59,10 +60,8 @@ func init() {
 // No hash-table acceleration; things here are small, and the tool is interactive.
 func (repl *Repl) findHandler(verbName string) *handlerInfo {
 	for _, entry := range handlerLookupTable {
-		for _, entryVerbName := range entry.verbNames {
-			if entryVerbName == verbName {
-				return &entry
-			}
+		if slices.Contains(entry.verbNames, verbName) {
+			return &entry
 		}
 	}
 	return nil

pkg/transformers/aaa_chain_transformer.go

@@ -151,7 +151,7 @@ func ChainTransformer(
 	}
 
 	intermediateDownstreamDoneChannels := make([]chan bool, n)
-	for i = 0; i < n; i++ {
+	for i = range n {
 		intermediateDownstreamDoneChannels[i] = make(chan bool, 1)
 	}
 

pkg/transformers/bar.go

@@ -246,13 +246,7 @@ func (tr *TransformerBar) processNoAuto(
 			if !ok {
 				continue
 			}
-			idx := int(float64(tr.width) * (floatValue - tr.lo) / (tr.hi - tr.lo))
-			if idx < 0 {
-				idx = 0
-			}
-			if idx > tr.width {
-				idx = tr.width
-			}
+			idx := min(max(int(float64(tr.width)*(floatValue-tr.lo)/(tr.hi-tr.lo)), 0), tr.width)
 			inrec.PutReference(fieldName, mlrval.FromString(tr.bars[idx]))
 		}
 
@@ -322,13 +316,7 @@ func (tr *TransformerBar) processAuto(
 				continue
 			}
 
-			idx := int((float64(tr.width) * (floatValue - lo) / (hi - lo)))
-			if idx < 0 {
-				idx = 0
-			}
-			if idx > tr.width {
-				idx = tr.width
-			}
+			idx := min(max(int((float64(tr.width)*(floatValue-lo)/(hi-lo))), 0), tr.width)
 
 			var buffer bytes.Buffer
 			buffer.WriteString("[")
@@ -342,9 +330,7 @@ func (tr *TransformerBar) processAuto(
 		}
 	}
 
-	for _, recordAndContext := range tr.recordsForAutoMode {
-		*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-	}
+	*outputRecordsAndContexts = append(*outputRecordsAndContexts, tr.recordsForAutoMode...)
 
 	*outputRecordsAndContexts = append(*outputRecordsAndContexts, inrecAndContext) // Emit the end-of-stream marker
 }

pkg/transformers/group_by.go

@@ -128,10 +128,7 @@ func (tr *TransformerGroupBy) Transform(
 
 	} else {
 		for outer := tr.recordListsByGroup.Head; outer != nil; outer = outer.Next {
-			recordListForGroup := outer.Value
-			for _, recordAndContext := range *recordListForGroup {
-				*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-			}
+			*outputRecordsAndContexts = append(*outputRecordsAndContexts, *outer.Value...)
 		}
 		*outputRecordsAndContexts = append(*outputRecordsAndContexts, inrecAndContext) // end-of-stream marker
 	}

pkg/transformers/group_like.go

@@ -108,10 +108,7 @@ func (tr *TransformerGroupLike) Transform(
 
 	} else {
 		for outer := tr.recordListsByGroup.Head; outer != nil; outer = outer.Next {
-			recordListForGroup := outer.Value
-			for _, recordAndContext := range *recordListForGroup {
-				*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-			}
+			*outputRecordsAndContexts = append(*outputRecordsAndContexts, *outer.Value...)
 		}
 		*outputRecordsAndContexts = append(*outputRecordsAndContexts, inrecAndContext) // end-of-stream marker
 	}

pkg/transformers/histogram.go

@@ -172,7 +172,7 @@ func NewTransformerHistogram(
 	countsByField := make(map[string][]int64)
 	for _, valueFieldName := range valueFieldNames {
 		countsByField[valueFieldName] = make([]int64, nbins)
-		for i := int64(0); i < nbins; i++ {
+		for i := range nbins {
 			countsByField[valueFieldName][i] = 0
 		}
 	}
@@ -323,7 +323,7 @@ func (tr *TransformerHistogram) emitAuto(
 	for _, valueFieldName := range tr.valueFieldNames {
 		vector := tr.vectorsByFieldName[valueFieldName]
 		n := len(vector)
-		for i := 0; i < n; i++ {
+		for i := range n {
 			value := vector[i]
 			if haveLoHi {
 				if lo > value {
@@ -347,7 +347,7 @@ func (tr *TransformerHistogram) emitAuto(
 		counts := tr.countsByField[valueFieldName]
 		lib.InternalCodingErrorIf(counts == nil)
 		n := len(vector)
-		for i := 0; i < n; i++ {
+		for i := range n {
 			value := vector[i]
 			if (value >= lo) && (value < hi) {
 				idx := int(((value - lo) * mul))
@@ -365,7 +365,7 @@ func (tr *TransformerHistogram) emitAuto(
 		countFieldNames[valueFieldName] = tr.outputPrefix + valueFieldName + "_count"
 	}
 
-	for i := int64(0); i < nbins; i++ {
+	for i := range nbins {
 		outrec := mlrval.NewMlrmapAsRecord()
 
 		outrec.PutReference(

pkg/transformers/join.go

@@ -573,7 +573,7 @@ func (tr *TransformerJoin) formAndEmitPairs(
 
 		// Add the joined-on fields to the new output record
 		n := len(tr.opts.leftJoinFieldNames)
-		for i := 0; i < n; i++ {
+		for i := range n {
 			// These arrays are already guaranteed same-length by CLI parser
 			leftJoinFieldName := tr.opts.leftJoinFieldNames[i]
 			outputJoinFieldName := tr.opts.outputJoinFieldNames[i]
@@ -625,10 +625,7 @@ func (tr *TransformerJoin) formAndEmitPairs(
 func (tr *TransformerJoin) emitLeftUnpairables(
 	outputRecordsAndContexts *[]*types.RecordAndContext, // list of *types.RecordAndContext
 ) {
-	// Loop over each to-be-paired-with record from the left file.
-	for _, leftRecordAndContext := range tr.leftUnpairableRecordsAndContexts {
-		*outputRecordsAndContexts = append(*outputRecordsAndContexts, leftRecordAndContext)
-	}
+	*outputRecordsAndContexts = append(*outputRecordsAndContexts, tr.leftUnpairableRecordsAndContexts...)
 }
 
 func (tr *TransformerJoin) emitLeftUnpairedBuckets(
@@ -637,9 +634,7 @@ func (tr *TransformerJoin) emitLeftUnpairedBuckets(
 	for pe := tr.leftBucketsByJoinFieldValues.Head; pe != nil; pe = pe.Next {
 		bucket := pe.Value
 		if !bucket.WasPaired {
-			for _, recordAndContext := range bucket.RecordsAndContexts {
-				*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-			}
+			*outputRecordsAndContexts = append(*outputRecordsAndContexts, bucket.RecordsAndContexts...)
 		}
 	}
 }

pkg/transformers/most_or_least_frequent.go

@@ -263,10 +263,7 @@ func (tr *TransformerMostOrLeastFrequent) Transform(
 		}
 
 		// Emit top n
-		outputLength := inputLength
-		if inputLength > tr.maxOutputLength {
-			outputLength = tr.maxOutputLength
-		}
+		outputLength := min(inputLength, tr.maxOutputLength)
 		for i := int64(0); i < outputLength; i++ {
 			outrec := mlrval.NewMlrmapAsRecord()
 			groupByFieldValues := tr.valuesForGroup[sortPairs[i].groupingKey]

pkg/transformers/nest.go

@@ -458,8 +458,8 @@ func (tr *TransformerNest) explodeValuesAcrossRecords(
 		svalue := mvalue.String()
 
 		// Not lib.SplitString so 'x=' will map to 'x=', rather than no field at all
-		pieces := strings.Split(svalue, tr.nestedFS)
-		for _, piece := range pieces {
+		pieces := strings.SplitSeq(svalue, tr.nestedFS)
+		for piece := range pieces {
 			outrec := inrec.Copy()
 			outrec.PutReference(fieldName, mlrval.FromString(piece))
 			*outputRecordsAndContexts = append(*outputRecordsAndContexts, types.NewRecordAndContext(outrec, &inrecAndContext.Context))

pkg/transformers/reorder.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 	"regexp"
+	"slices"
 	"strings"
 
 	"github.com/johnkerl/miller/v6/pkg/cli"
@@ -180,7 +181,7 @@ func NewTransformerReorder(
 				tr.recordTransformerFunc = tr.reorderToStartWithRegex
 			} else {
 				tr.recordTransformerFunc = tr.reorderToStartNoRegex
-				lib.ReverseStringList(tr.fieldNames)
+				slices.Reverse(tr.fieldNames)
 			}
 		}
 	} else {

pkg/transformers/shuffle.go

@@ -104,12 +104,12 @@ func (tr *TransformerShuffle) Transform(
 		// * Make a pseudorandom permutation using pseudorandom swaps in the image map.
 		n := int64(len(tr.recordsAndContexts))
 		images := make([]int64, n)
-		for i := int64(0); i < n; i++ {
+		for i := range n {
 			images[i] = i
 		}
 		unusedStart := int64(0)
 		numUnused := n
-		for i := int64(0); i < n; i++ {
+		for i := range n {
 			// Select a pseudorandom element from the pool of unused images.
 			u := lib.RandRange(unusedStart, unusedStart+numUnused)
 			temp := images[u]
@@ -127,7 +127,7 @@ func (tr *TransformerShuffle) Transform(
 		// Transfer from input array to output list. Because permutations are one-to-one maps,
 		// all input records have ownership transferred exactly once. So, there are no
 		// records to copy here.
-		for i := int64(0); i < n; i++ {
+		for i := range n {
 			*outputRecordsAndContexts = append(*outputRecordsAndContexts, array[images[i]])
 		}
 

pkg/transformers/sort.go

@@ -456,14 +456,10 @@ func (tr *TransformerSort) Transform(
 		// Now output the groups
 		for _, groupingKeyAndMlrvals := range groupingKeysAndMlrvals {
 			recordsInGroup := tr.recordListsByGroup.Get(groupingKeyAndMlrvals.groupingKey)
-			for _, recordAndContext := range *recordsInGroup {
-				*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-			}
+			*outputRecordsAndContexts = append(*outputRecordsAndContexts, *recordsInGroup...)
 		}
 
-		for _, recordAndContext := range tr.spillGroup {
-			*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-		}
+		*outputRecordsAndContexts = append(*outputRecordsAndContexts, tr.spillGroup...)
 
 		*outputRecordsAndContexts = append(*outputRecordsAndContexts, inrecAndContext) // end-of-stream marker
 	}

pkg/transformers/stats1.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"regexp"
+	"slices"
 	"strings"
 
 	"github.com/johnkerl/miller/v6/pkg/cli"
@@ -180,7 +181,7 @@ func transformerStats1ParseCLI(
 			if err != nil {
 				return nil, err
 			}
-			groupByFieldNameList = lib.CopyStringArray(valueFieldNameList)
+			groupByFieldNameList = slices.Clone(valueFieldNameList)
 
 		} else if opt == "-i" {
 			doInterpolatedPercentiles = true

pkg/transformers/tail.go

@@ -161,10 +161,7 @@ func (tr *TransformerTail) Transform(
 
 	} else {
 		for outer := tr.recordListsByGroup.Head; outer != nil; outer = outer.Next {
-			recordListForGroup := outer.Value
-			for _, recordAndContext := range *recordListForGroup {
-				*outputRecordsAndContexts = append(*outputRecordsAndContexts, recordAndContext)
-			}
+			*outputRecordsAndContexts = append(*outputRecordsAndContexts, *outer.Value...)
 		}
 		*outputRecordsAndContexts = append(*outputRecordsAndContexts, inrecAndContext) // end-of-stream marker
 	}

pkg/transformers/utils/join_bucket_keeper.go

@@ -581,7 +581,7 @@ func compareLexically(
 ) int {
 	lib.InternalCodingErrorIf(len(leftFieldValues) != len(rightFieldValues))
 	n := len(leftFieldValues)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		left := leftFieldValues[i].String()
 		right := rightFieldValues[i].String()
 		// Returns -1, 0, 1 as left <, ==, > right

pkg/transformers/utils/stats1_accumulators.go

@@ -515,13 +515,13 @@ func (acc *Stats1MeanAbsDevAccumulator) Emit() *mlrval.Mlrval {
 	mn := mlrval.FromInt(int64(n))
 
 	mean := mlrval.FromInt(0)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		mean = bifs.BIF_plus_binary(mean, acc.samples[i])
 	}
 	mean = bifs.BIF_divide(mean, mn)
 
 	meanAbsDev := mlrval.FromInt(0)
-	for i := 0; i < n; i++ {
+	for i := range n {
 		diff := bifs.BIF_minus_binary(mean, acc.samples[i])
 		meanAbsDev = bifs.BIF_plus_binary(meanAbsDev, bifs.BIF_abs(diff))
 	}