increased test coverage and splitted some utility functions by OS

builtin-iterator.go

@@ -23,9 +23,11 @@ func parseRunArgs(localCtx ExprContext, args map[string]any) (it Iterator, op Fu
 		return
 	}
 
-	if op, ok = args[iterParamOperator].(Functor); !ok && args[iterParamOperator] != nil {
+	if args[iterParamOperator] != nil {
-		err = fmt.Errorf("paramter %q must be a function, passed %v [%s]", iterParamOperator, args[iterParamOperator], TypeName(args[iterParamOperator]))
+		if op, ok = args[iterParamOperator].(Functor); !ok || op == nil {
-		return
+			err = fmt.Errorf("paramter %q must be a function, passed %v [%s]", iterParamOperator, args[iterParamOperator], TypeName(args[iterParamOperator]))
+			return
+		}
 	}
 
 	var vars *DictType
@@ -51,7 +53,7 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 	var ok bool
 	var op Functor
 	var v any
-	var usingDefaultOp = false
+	// var usingDefaultOp = false
 	var params map[string]any
 	var item any
 
@@ -60,24 +62,27 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 
 	if it, op, err = parseRunArgs(localCtx, args); err != nil {
 		return
-	} else if op == nil {
+		// } else if op == nil {
-		op = NewGolangFunctor(printLnFunc)
+		// 	op = NewGolangFunctor(printLnFunc)
-		usingDefaultOp = true
+		// 	usingDefaultOp = true
 	}
 
 	for item, err = it.Next(); err == nil; item, err = it.Next() {
-		if usingDefaultOp {
+		// if usingDefaultOp {
-			params = map[string]any{ParamItem: []any{item}}
+		// 	params = map[string]any{ParamItem: []any{item}}
-		} else {
+		// } else {
-			params = map[string]any{ParamIndex: it.Index(), ParamItem: item}
+		// params = map[string]any{ParamIndex: it.Index(), ParamItem: item}
-		}
+		// }
 
-		if v, err = op.InvokeNamed(localCtx, iterParamOperator, params); err != nil {
+		if op != nil {
-			break
+			params = map[string]any{ParamIndex: it.Index(), ParamItem: item}
-		} else {
+			if v, err = op.InvokeNamed(localCtx, iterParamOperator, params); err != nil {
-			var success bool
-			if success, ok = ToBool(v); !success || !ok {
 				break
+			} else {
+				var success bool
+				if success, ok = ToBool(v); !success || !ok {
+					break
+				}
 			}
 		}
 	}
@@ -86,6 +91,9 @@ func runFunc(ctx ExprContext, name string, args map[string]any) (result any, err
 		err = nil
 	}
 	if err == nil {
+		if op == nil {
+			ctx.UnsafeSetVar(iterVarStatus, it.Count())
+		}
 		result, _ = localCtx.GetVar(iterVarStatus)
 	}
 	return

builtin-os-file-iter.go

@@ -0,0 +1,149 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// builtin-os-file.go
+package expr
+
+import (
+	"fmt"
+	"io"
+	"slices"
+)
+
+const paramHandleOrPath = "handle-or-path"
+const fileReadTextIteratorType = "fileReadTextIterator"
+
+type fileReadTextIterator struct {
+	osReader  *osReader
+	index     int
+	count     int
+	line      string
+	autoClose bool
+}
+
+func newReadTextIterator(r *osReader, autoClose bool) *fileReadTextIterator {
+	return &fileReadTextIterator{osReader: r, index: -1, autoClose: autoClose}
+}
+
+func (it *fileReadTextIterator) TypeName() string {
+	return fileReadTextIteratorType
+}
+
+func (it *fileReadTextIterator) String() string {
+	if it.osReader != nil && it.osReader.fh != nil {
+		return fmt.Sprintf("$(%s@%q)", fileReadTextIteratorType, it.osReader.fh.Name())
+	}
+	return fmt.Sprintf("$(%s@<nil>)", fileReadTextIteratorType)
+}
+
+func (it *fileReadTextIterator) Count() int {
+	return it.count
+}
+
+func (it *fileReadTextIterator) Next() (item any, err error) { // must return io.EOF after the last item
+	if it.osReader.fh != nil {
+		if it.line, err = it.osReader.reader.ReadString('\n'); err == nil {
+			it.index++
+			it.count++
+			item = it.line[0 : len(it.line)-1]
+		} else if it.autoClose {
+			it.Clean()
+		}
+	}
+	return
+}
+
+func (it *fileReadTextIterator) Current() (item any, err error) {
+	if len(it.line) > 0 {
+		item = it.line[0 : len(it.line)-1]
+	}
+	return
+}
+
+func (it *fileReadTextIterator) Index() int {
+	return it.index
+}
+
+func (it *fileReadTextIterator) Reset() (err error) {
+	if _, err = it.osReader.fh.Seek(0, io.SeekStart); err == nil {
+		it.index = -1
+		it.count = 0
+		it.line = ""
+	}
+	return
+}
+
+func (it *fileReadTextIterator) HasOperation(name string) bool {
+	return slices.Contains([]string{NextName, ResetName, IndexName, CountName, CurrentName, CleanName}, name)
+}
+
+func (it *fileReadTextIterator) Clean() (err error) {
+	if it.osReader.fh != nil {
+		if err = it.osReader.fh.Close(); err == nil {
+			it.osReader = nil
+		}
+	}
+	return nil
+}
+
+func (it *fileReadTextIterator) CallOperation(name string, args map[string]any) (v any, err error) {
+	switch name {
+	case NextName:
+		v, err = it.Next()
+	case ResetName:
+		err = it.Reset()
+	case CleanName:
+		err = it.Clean()
+	case IndexName:
+		v = int64(it.Index())
+	case CurrentName:
+		v, err = it.Current()
+	case CountName:
+		v = it.count
+	default:
+		err = errNoOperation(name)
+	}
+	return
+}
+
+func fileReadIteratorFunc(ctx ExprContext, name string, args map[string]any) (result any, err error) {
+	var handle *osReader
+	var invalidFileHandle any
+	var ok, autoClose bool
+
+	result = nil
+	if handle, ok = args[paramHandleOrPath].(*osReader); !ok {
+		if fileName, ok := args[paramHandleOrPath].(string); ok && len(fileName) > 0 {
+			var handleAny any
+			if handleAny, err = openFileFunc(ctx, name, map[string]any{ParamFilepath: fileName}); err != nil {
+				return
+			}
+			if handleAny != nil {
+				handle = handleAny.(*osReader)
+				autoClose = true
+			}
+		} else {
+			invalidFileHandle = args[paramHandleOrPath]
+		}
+	}
+
+	if handle != nil {
+		result = newReadTextIterator(handle, autoClose)
+
+	}
+
+	if err == nil && (handle == nil || invalidFileHandle != nil) {
+		err = errInvalidFileHandle(name, invalidFileHandle)
+	}
+	return
+}
+
+// func ImportOsIterFuncs(ctx ExprContext) {
+// 	ctx.RegisterFunc("fileReadIterator", NewGolangFunctor(fileReadIteratorFunc), TypeIterator, []ExprFuncParam{
+// 		NewFuncParam(paramHandleOrPath),
+// 	})
+// }
+
+// func init() {
+// 	RegisterBuiltinModule("os.file", ImportOsIterFuncs, "Operating system file iterator functions")
+// }

builtin-os-file.go

@@ -250,6 +250,10 @@ func ImportOsFuncs(ctx ExprContext) {
 	ctx.RegisterFunc("fileReadTextAll", NewGolangFunctor(fileReadTextAllFunc), TypeString, []ExprFuncParam{
 		NewFuncParam(ParamHandle),
 	})
+
+	ctx.RegisterFunc("fileReadIterator", NewGolangFunctor(fileReadIteratorFunc), TypeIterator, []ExprFuncParam{
+		NewFuncParam(paramHandleOrPath),
+	})
 }
 
 func init() {

common-type-names.go

@@ -13,6 +13,7 @@ const (
 	TypeFileHandle    = "file-handle"
 	TypeInt           = "integer"
 	TypeItem          = "item"
+	TypeIterator      = "iterator"
 	TypeNumber        = "number"
 	TypePair          = "pair"
 	TypeString        = "string"

dict-iterator.go

@@ -68,42 +68,54 @@ func (it *DictIterator) makeKeys(m map[any]any, sort sortType) {
 func NewDictIterator(dict *DictType, args []any) (it *DictIterator, err error) {
 	var sortType = sortTypeNone
 	var s string
-	it = &DictIterator{a: dict, count: 0, index: -1, keys: nil, iterMode: dictIterModeKeys}
+	var argAny any
+
+	dictIt := &DictIterator{a: dict, count: 0, index: -1, keys: nil, iterMode: dictIterModeKeys}
 	if len(args) > 0 {
-		if s, err = ToGoString(args[0], "sort type"); err == nil {
+		argAny = args[0]
-			switch strings.ToLower(s) {
+	} else {
-			case "a", "asc":
+		argAny = "default"
-				sortType = sortTypeAsc
+	}
-			case "d", "desc":
+	if s, err = ToGoString(argAny, "sort type"); err == nil {
-				sortType = sortTypeDesc
+		switch strings.ToLower(s) {
-			case "n", "none", "nosort", "no-sort":
+		case "a", "asc":
-				sortType = sortTypeNone
+			sortType = sortTypeAsc
-			case "", "default":
+		case "d", "desc":
-				sortType = sortTypeDefault
+			sortType = sortTypeDesc
-			default:
+		case "n", "none", "nosort", "no-sort":
-				err = fmt.Errorf("invalid sort type %q", s)
+			sortType = sortTypeNone
+		case "", "default":
+			sortType = sortTypeDefault
+		default:
+			err = fmt.Errorf("invalid sort type %q", s)
+		}
+
+		if err == nil {
+			if len(args) > 1 {
+				argAny = args[1]
+			} else {
+				argAny = "default"
 			}
 
-			if err == nil && len(args) > 1 {
+			if s, err = ToGoString(argAny, "iteration mode"); err == nil {
-				if s, err = ToGoString(args[1], "iteration mode"); err == nil {
+				switch strings.ToLower(s) {
-					switch strings.ToLower(s) {
+				case "k", "key", "keys":
-					case "k", "key", "keys":
+					dictIt.iterMode = dictIterModeKeys
-						it.iterMode = dictIterModeKeys
+				case "v", "value", "values":
-					case "v", "value", "values":
+					dictIt.iterMode = dictIterModeValues
-						it.iterMode = dictIterModeValues
+				case "i", "item", "items":
-					case "i", "item", "items":
+					dictIt.iterMode = dictIterModeItems
-						it.iterMode = dictIterModeItems
+				case "", "default":
-					case "", "default":
+					dictIt.iterMode = dictIterModeKeys
-						it.iterMode = dictIterModeKeys
+				default:
-					default:
+					err = fmt.Errorf("invalid iteration mode %q", s)
-						err = fmt.Errorf("invalid iteration mode %q", s)
-					}
 				}
 			}
 		}
 	}
-	it.makeKeys(*dict, sortType)
+
-	return
+	dictIt.makeKeys(*dict, sortType)
+	return dictIt, err
 }
 
 func NewMapIterator(m map[any]any) (it *DictIterator) {
@@ -117,7 +129,7 @@ func (it *DictIterator) String() string {
 	if it.a != nil {
 		l = len(*it.a)
 	}
-	return fmt.Sprintf("$(#%d)", l)
+	return fmt.Sprintf("$({#%d})", l)
 }
 
 func (it *DictIterator) TypeName() string {

doc/Expr.adoc

@@ -1087,6 +1087,8 @@ The "base" builtin module provides functions for type checking and type conversi
 
 .Other functions
 * <<_eval,eval()>>
+* <<_set,set()>>
+* <<_unset,unset()>>
 * <<_var,var()>>
 
 
@@ -1318,6 +1320,32 @@ This function allows you to define variables whose names must include special ch
 `>>>` [blue]`var("gain%", var("$x")+1)` +
 [green]`13`
 
+===== set
+Syntax: +
+ `{4sp}set(<string-expr>, <expr>) -> any`
+
+This function allows you to set the value of a variable whose name can include special characters. The first parameter is the name of the variable and the second parameter is the new value to assign to that variable.
+
+It is equivalent to the first form of the var() function, but it is more explicit about the intent of changing the value of an existing variable. 
+
+.Examples
+`>>>` [blue]`set("$x", 100)` +
+[green]`100` +
+`>>>` [blue]`var("$x")` +
+[green]`100` +
+
+===== unset()
+Syntax: +
+ `{4sp}unset(<string-expr>) -> any`
+
+This function allows you to unset a variable whose name can include special characters. The parameter is the name of the variable to unset.
+
+.Examples
+`>>>` [blue]`unset("$x")` +
+[green]`nil` +
+`>>>` [blue]`var("$x")` +
+[red]`Eval Error: var(): unknown variable "$x"`
+
 ==== Module "fmt"
 
 ===== print()
@@ -1325,18 +1353,31 @@ This function allows you to define variables whose names must include special ch
 ===== println()
 
 ==== Module "import"
+Module actiovation: +
+
 ===== _import()_
-[blue]_import([grey]#<source-file>#)_ -- loads the multi-expression contained in the specified source and returns its value.
+Syntax: +
+`{4sp}import(<source-file>)`
+
+Loads the multi-expression contained in the specified source and returns its value.
 
 ===== _importAll()_
 
 ==== Module "iterator"
 
 ===== run()
+Syntax: +
+`{4sp}run(<iterator>, <operator>, <vars>) -> any`
+
+Iterates over the specified iterator and applies the specified operator to the current value of the iterator.
 
 ==== Module "math.arith"
 Currently, the "math.arith" module provides two functions, add() and mul(), that perform addition and multiplication of an arbitrary number of parameters. More functions will be added in the future.
 
+* <<_add,add()>>
+* <<_mul,mul()>>
+
+
 ===== add()
 Syntax: +
 `{4sp}add(<num-expr1>, <num-expr2>, ...) -> any` +

import-utils.go

@@ -76,6 +76,12 @@ func isFile(filePath string) bool {
 
 func searchAmongPath(filename string, dirList []string) (filePath string) {
 	var err error
+
+	suffix := SHAREDLIBRARY_EXTENSION
+	if strings.HasSuffix(filename, ".debug") {
+		suffix += ".debug"
+	}
+
 	for _, dir := range dirList {
 		if dir, err = ExpandPath(dir); err != nil {
 			continue
@@ -84,6 +90,12 @@ func searchAmongPath(filename string, dirList []string) (filePath string) {
 			filePath = fullPath
 			break
 		}
+
+		subdir := strings.TrimSuffix(filename, suffix)
+		if fullPath := path.Join(dir, subdir, filename); isFile(fullPath) {
+			filePath = fullPath
+			break
+		}
 	}
 	return
 }

iter-factory.go

@@ -0,0 +1,25 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// iter-factory.go
+package expr
+
+func NewIterator(value any) (it Iterator, err error) {
+	if value == nil {
+		return NewArrayIterator([]any{}), nil
+	}
+
+	switch v := value.(type) {
+	case *ListType:
+		it = NewListIterator(v, nil)
+	case *DictType:
+		it, err = NewDictIterator(v, nil)
+	case []any:
+		it = NewArrayIterator(v)
+	case Iterator:
+		it = v
+	default:
+		it = NewArrayIterator([]any{value})
+	}
+	return
+}

iterator.go

@@ -27,6 +27,7 @@ const (
 
 type Iterator interface {
 	Typer
+	fmt.Stringer
 	Next() (item any, err error) // must return io.EOF after the last item
 	Current() (item any, err error)
 	Index() int

lib-ext-darwin.go

@@ -0,0 +1,9 @@
+//go:build darwin
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// lib-ext-darwin.go
+package expr
+
+const SHAREDLIBRARY_EXTENSION = ".dylib"

lib-ext-linux.go

@@ -0,0 +1,9 @@
+//go:build linux
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// lib-ext-linux.go
+package expr
+
+const SHAREDLIBRARY_EXTENSION = ".so"

lib-ext-windows.go

@@ -0,0 +1,9 @@
+//go:build windows
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// lib-ext-windows.go
+package expr
+
+const SHAREDLIBRARY_EXTENSION = ".dll"

list-iterator.go

@@ -62,27 +62,12 @@ func NewArrayIterator(array []any) (it *ListIterator) {
 	return
 }
 
-func NewAnyIterator(value any) (it *ListIterator) {
-	if value == nil {
-		it = NewArrayIterator([]any{})
-	} else if list, ok := value.(*ListType); ok {
-		it = NewListIterator(list, nil)
-	} else if array, ok := value.([]any); ok {
-		it = NewArrayIterator(array)
-	} else if it1, ok := value.(*ListIterator); ok {
-		it = it1
-	} else {
-		it = NewArrayIterator([]any{value})
-	}
-	return
-}
-
 func (it *ListIterator) String() string {
 	var l = 0
 	if it.a != nil {
 		l = len(*it.a)
 	}
-	return fmt.Sprintf("$(#%d)", l)
+	return fmt.Sprintf("$([#%d])", l)
 }
 
 func (it *ListIterator) TypeName() string {

list-type.go

@@ -26,9 +26,9 @@ func newList(listAny []any) (list *ListType) {
 func NewList(listAny []any) (list *ListType) {
 	if listAny != nil {
 		ls := make(ListType, len(listAny))
-//		for i, item := range listAny {
+		//		for i, item := range listAny {
-//			ls[i] = item
+		//			ls[i] = item
-//		}
+		//		}
 		copy(ls, listAny)
 		list = &ls
 	}
@@ -53,14 +53,14 @@ func ListFromStrings(stringList []string) (list *ListType) {
 }
 
 func (ls *ListType) ToString(opt FmtOpt) (s string) {
-        indent := GetFormatIndent(opt)
+	indent := GetFormatIndent(opt)
-        flags := GetFormatFlags(opt)
+	flags := GetFormatFlags(opt)
 
 	var sb strings.Builder
 	sb.WriteByte('[')
 	if len(*ls) > 0 {
-                innerOpt := MakeFormatOptions(flags, indent+1)
+		innerOpt := MakeFormatOptions(flags, indent+1)
-                nest := strings.Repeat("  ", indent+1)
+		nest := strings.Repeat("  ", indent+1)
 
 		if flags&MultiLine != 0 {
 			sb.WriteByte('\n')
@@ -129,6 +129,20 @@ func (ls *ListType) contains(t *ListType) (answer bool) {
 	return
 }
 
+func (ls1 *ListType) Equals(ls2 ListType) (answer bool) {
+	if ls2 != nil && len(*ls1) == len(ls2) {
+		answer = true
+		for index, i1 := range *ls1 {
+			// if i1 != (ls2)[index] {
+			if !reflect.DeepEqual(i1, ls2[index]) {
+				answer = false
+				break
+			}
+		}
+	}
+	return
+}
+
 func (list *ListType) indexDeepSameCmp(target any) (index int) {
 	var eq bool
 	var err error
@@ -193,3 +207,6 @@ func (list *ListType) setItem(index int64, value any) (err error) {
 	return
 }
 
+func (list *ListType) appendItem(value any) {
+	*list = append(*list, value)
+}

operator-builtin.go

@@ -31,7 +31,10 @@ func evalBuiltin(ctx ExprContext, opTerm *term) (v any, err error) {
 		count, err = ImportInContextByGlobPattern(module)
 	} else {
 		var moduleSpec any
-		it := NewAnyIterator(childValue)
+		var it Iterator
+		if it, err = NewIterator(childValue); err != nil {
+			return
+		}
 		for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
 			if module, ok := moduleSpec.(string); ok {
 				if ImportInContext(module) {

operator-digest.go

@@ -0,0 +1,70 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-digest.go
+package expr
+
+import (
+	"fmt"
+	"io"
+)
+
+//-------- digest term
+
+func newDigestTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priIterOp,
+		evalFunc: evalDigest,
+	}
+}
+
+func evalDigest(ctx ExprContext, opTerm *term) (v any, err error) {
+	var leftValue, rightValue any
+	var it Iterator
+	var item, lastValue any
+
+	if err = opTerm.checkOperands(); err != nil {
+		return
+	}
+
+	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+		return
+	}
+
+	if it, err = NewIterator(leftValue); err != nil {
+		return nil, fmt.Errorf("left operand of DIGEST must be an iterable data-source; got %s", TypeName(leftValue))
+	}
+
+	lastValue = nil
+	for item, err = it.Next(); err == nil; item, err = it.Next() {
+		ctx.SetVar("_", item)
+		ctx.SetVar("_index", it.Index())
+		ctx.SetVar("_count", it.Count())
+		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+			if rightValue == nil {
+				break
+			} else {
+				lastValue = rightValue
+			}
+		}
+		ctx.DeleteVar("_count")
+		ctx.DeleteVar("_index")
+		ctx.DeleteVar("_")
+		if err != nil {
+			break
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	v = lastValue
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymKwDigest, newDigestTerm)
+}

operator-filter.go

@@ -0,0 +1,72 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-filter.go
+package expr
+
+import (
+	"fmt"
+	"io"
+)
+
+//-------- map term
+
+func newFilterTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priIterOp,
+		evalFunc: evalFilter,
+	}
+}
+
+func evalFilter(ctx ExprContext, opTerm *term) (v any, err error) {
+	var leftValue, rightValue any
+	var it Iterator
+	var item any
+
+	if err = opTerm.checkOperands(); err != nil {
+		return
+	}
+
+	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+		return
+	}
+
+	if it, err = NewIterator(leftValue); err != nil {
+		return nil, fmt.Errorf("left operand of FILTER must be an iterable data-source; got %s", TypeName(leftValue))
+	}
+
+	values := newListA()
+	for item, err = it.Next(); err == nil; item, err = it.Next() {
+		ctx.SetVar("_", item)
+		ctx.SetVar("_index", it.Index())
+		ctx.SetVar("_count", it.Count())
+		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+			if success, valid := ToBool(rightValue); valid {
+				if success {
+					values.appendItem(item)
+				}
+			} else {
+				err = fmt.Errorf("filter expression must return a boolean or a castable to boolean, got %v [%T]", rightValue, rightValue)
+			}
+		}
+		ctx.DeleteVar("_count")
+		ctx.DeleteVar("_index")
+		ctx.DeleteVar("_")
+		if err != nil {
+			break
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	v = values
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymKwFilter, newFilterTerm)
+}

operator-join.go

@@ -0,0 +1,65 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-join.go
+package expr
+
+import (
+	"fmt"
+	"io"
+)
+
+//-------- join term
+
+func newJoinTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priIterOp,
+		evalFunc: evalJoin,
+	}
+}
+
+func evalJoin(ctx ExprContext, opTerm *term) (v any, err error) {
+	var leftValue, rightValue any
+	var itLeft, itRight Iterator
+	var item any
+
+	if err = opTerm.checkOperands(); err != nil {
+		return
+	}
+
+	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+		return
+	}
+
+	if rightValue, err = opTerm.children[1].compute(ctx); err != nil {
+		return
+	}
+
+	if itLeft, err = NewIterator(leftValue); err != nil {
+		return nil, fmt.Errorf("left operand of JOIN must be an iterable data-source; got %s", TypeName(leftValue))
+	}
+
+	if itRight, err = NewIterator(rightValue); err != nil {
+		return nil, fmt.Errorf("right operand of JOIN must be an iterable data-source; got %s", TypeName(rightValue))
+	}
+
+	values := newListA()
+	for _, it := range []Iterator{itLeft, itRight} {
+		for item, err = it.Next(); err == nil; item, err = it.Next() {
+			values.appendItem(item)
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	v = values
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymKwJoin, newJoinTerm)
+}

operator-map.go

@@ -0,0 +1,66 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-map.go
+package expr
+
+import (
+	"fmt"
+	"io"
+)
+
+//-------- map term
+
+func newMapTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priIterOp,
+		evalFunc: evalMap,
+	}
+}
+
+func evalMap(ctx ExprContext, opTerm *term) (v any, err error) {
+	var leftValue, rightValue any
+	var it Iterator
+	var item any
+
+	if err = opTerm.checkOperands(); err != nil {
+		return
+	}
+
+	if leftValue, err = opTerm.children[0].compute(ctx); err != nil {
+		return
+	}
+
+	if it, err = NewIterator(leftValue); err != nil {
+		return nil, fmt.Errorf("left operand of MAP must be an iterable data-source; got %s", TypeName(leftValue))
+	}
+
+	values := newListA()
+	for item, err = it.Next(); err == nil; item, err = it.Next() {
+		ctx.SetVar("_", item)
+		ctx.SetVar("_index", it.Index())
+		ctx.SetVar("_count", it.Count())
+		if rightValue, err = opTerm.children[1].compute(ctx); err == nil {
+			values.appendItem(rightValue)
+		}
+		ctx.DeleteVar("_count")
+		ctx.DeleteVar("_index")
+		ctx.DeleteVar("_")
+		if err != nil {
+			break
+		}
+	}
+	if err == io.EOF {
+		err = nil
+	}
+	v = values
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymKwMap, newMapTerm)
+}

plugins.go

@@ -31,11 +31,11 @@ func pluginExists(name string) (exists bool) {
 func makePluginName(name string) (decorated string) {
 	var template string
 	if execName, err := os.Executable(); err != nil || !strings.Contains(execName, "debug") {
-		template = "expr-%s-plugin.so"
+		template = "expr-%s-plugin%s"
 	} else {
-		template = "expr-%s-plugin.so.debug"
+		template = "expr-%s-plugin%s.debug"
 	}
-	decorated = fmt.Sprintf(template, name)
+	decorated = fmt.Sprintf(template, name, SHAREDLIBRARY_EXTENSION)
 	return
 }
 
@@ -93,10 +93,12 @@ func importPlugin( /*ctx ExprContext,*/ dirList []string, name string) (err erro
 
 func importPluginFromSearchPath(name any) (count int, err error) {
 	var moduleSpec any
-
+	var it Iterator
 	dirList := buildSearchDirList("plugin", ENV_EXPR_PLUGIN_PATH)
 	count = 0
-	it := NewAnyIterator(name)
+	if it, err = NewIterator(name); err != nil {
+		return
+	}
 	for moduleSpec, err = it.Next(); err == nil; moduleSpec, err = it.Next() {
 		if module, ok := moduleSpec.(string); ok {
 			if err = importPlugin(dirList, module); err != nil {

scanner.go

@@ -210,14 +210,14 @@ func (scanner *scanner) fetchNextToken() (tk *Token) {
 				tk = scanner.makeToken(SymQuote, ch)
 				escape = false
 			} else {
-				tk = scanner.fetchString(ch)
+				tk = scanner.fetchString(ch, true)
 			}
 		case '"':
 			if escape {
 				tk = scanner.makeToken(SymDoubleQuote, ch)
 				escape = false
 			} else {
-				tk = scanner.fetchString(ch)
+				tk = scanner.fetchString(ch, true)
 			}
 		case '`':
 			tk = scanner.makeToken(SymBackTick, ch)
@@ -315,6 +315,14 @@ func (scanner *scanner) fetchNextToken() (tk *Token) {
 				tk.source += ")"
 			} else if next == '$' {
 				tk = scanner.moveOn(SymDoubleDollar, ch, next)
+			} else if next == '{' {
+				scanner.readChar()
+				if tk = scanner.fetchString('}', false); tk != nil {
+					tk.Sym = SymIdentifier
+				}
+			} else if next == '_' || (next >= 'a' && next <= 'z') || (next >= 'A' && next <= 'Z') {
+				scanner.readChar()
+				tk = scanner.fetchIdentifier(next)
 			} else {
 				tk = scanner.makeToken(SymDollar, ch)
 			}
@@ -590,7 +598,7 @@ func (scanner *scanner) fetchUntil(sym Symbol, allowEos bool, endings ...byte) (
 	return
 }
 
-func (scanner *scanner) fetchString(termCh byte) (tk *Token) {
+func (scanner *scanner) fetchString(termCh byte, addQuote bool) (tk *Token) {
 	var err error
 	var ch, prev byte
 	var sb strings.Builder
@@ -628,7 +636,11 @@ func (scanner *scanner) fetchString(termCh byte) (tk *Token) {
 		}
 	} else {
 		txt := sb.String()
-		tk = scanner.makeValueToken(SymString, `"`+txt+`"`, txt)
+		if addQuote {
+			tk = scanner.makeValueToken(SymString, `"`+txt+`"`, txt)
+		} else {
+			tk = scanner.makeValueToken(SymString, txt, txt)
+		}
 	}
 	return
 }

symbol-map.go

@@ -135,6 +135,10 @@ func init() {
 		SymKwNot:     {"not", symClassOperator, posInfix},
 		SymKwOr:      {"or", symClassOperator, posInfix},
 		SymKwBut:     {"but", symClassOperator, posInfix},
+		SymKwMap:     {"map", symClassOperator, posInfix},
+		SymKwFilter:  {"filter", symClassOperator, posInfix},
+		SymKwDigest:  {"digest", symClassOperator, posInfix},
+		SymKwJoin:    {"join", symClassOperator, posInfix},
 		SymKwFunc:    {"func(", symClassDeclaration, posPrefix},
 		SymKwBuiltin: {"builtin", symClassOperator, posPrefix},
 		SymKwPlugin:  {"plugin", symClassOperator, posPrefix},

symbol.go

@@ -119,6 +119,10 @@ const (
 	SymKwPlugin
 	SymKwIn
 	SymKwInclude
+	SymKwMap
+	SymKwFilter
+	SymKwDigest
+	SymKwJoin
 	SymKwNil
 	SymKwUnset
 )
@@ -135,9 +139,13 @@ func init() {
 		"FUNC":    SymKwFunc,
 		"IN":      SymKwIn,
 		"INCLUDE": SymKwInclude,
+		"MAP":     SymKwMap,
+		"FILTER":  SymKwFilter,
 		"NOT":     SymKwNot,
 		"OR":      SymKwOr,
 		"NIL":     SymKwNil,
 		"UNSET":   SymKwUnset,
+		"DIGEST":  SymKwDigest,
+		"JOIN":    SymKwJoin,
 	}
 }

t_builtin-iterator_test.go

@@ -21,10 +21,11 @@ func TestFuncRun(t *testing.T) {
 		/*   7 */ {`builtin "iterator"; run($(1,2,3), func(){1}, "prrr")`, nil, `paramter "vars" must be a dictionary, passed prrr [string]`},
 		/*   8 */ {`builtin "iterator"; run($(1,2,3), operator=nil)`, nil, nil},
 		/*   9 */ {`builtin "iterator"; run($(1,2,3), operatorx=nil)`, nil, `run(): unknown param "operatorx"`},
+		/*   10 */ {`builtin ["os.file", "iterator"]; it = fileReadIterator("test-file.txt"); run(it)`, nil, nil},
 	}
 
 	//t.Setenv("EXPR_PATH", ".")
 
-	//runTestSuiteSpec(t, section, inputs, 1)
+	runTestSuiteSpec(t, section, inputs, 10)
-	runTestSuite(t, section, inputs)
+	// runTestSuite(t, section, inputs)
 }

t_builtin-os-file_test.go

@@ -5,6 +5,7 @@
 package expr
 
 import (
+	"io"
 	"testing"
 )
 
@@ -26,10 +27,16 @@ func TestFuncOs(t *testing.T) {
 		/*  13 */ {`builtin "os.file"; handle=fileClose(123)`, nil, `fileClose(): invalid file handle`},
 		/*  14 */ {`builtin "os.file"; handle=fileOpen("/tmp/dummy"); c=fileReadTextAll(handle); fileClose(handle); c`, "bye-bye", nil},
 		/*  15 */ {`builtin "os.file"; c=fileReadTextAll(123)`, nil, `fileReadTextAll(): invalid file handle 123 [int64]`},
+		/*  16 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it++`, "uno", nil},
+		/*  17 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it++;it++;it++`, nil, io.EOF.Error()},
+		/*  18 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); it.clean`, nil, nil},
+		/*  19 */ {`builtin "os.file"; it=fileReadIterator("test-file.txt"); string(it)`, `$(fileReadTextIterator@"test-file.txt")`, nil},
+		/*  20 */ {`builtin "os.file"; handle=fileOpen("/etc/hosts"); fileClose(handle); string(handle)`, `reader`, nil},
+		/*  21 */ {`builtin "os.file"; handle=fileCreate("/tmp/dummy"); fileClose(handle); string(handle)`, `writer`, nil},
 	}
 
 	// t.Setenv("EXPR_PATH", ".")
 
-	//runTestSuiteSpec(t, section, inputs, 2)
+	// runTestSuiteSpec(t, section, inputs, 19)
 	runTestSuite(t, section, inputs)
 }

t_common_test.go

@@ -72,6 +72,7 @@ func doTest(t *testing.T, ctx ExprContext, section string, input *inputType, cou
 	var expr Expr
 	var gotResult any
 	var gotErr error
+	var eq, eqDone bool
 
 	wantErr := getWantedError(input)
 
@@ -90,7 +91,18 @@ func doTest(t *testing.T, ctx ExprContext, section string, input *inputType, cou
 		gotResult, gotErr = expr.Eval(ctx)
 	}
 
-	eq := reflect.DeepEqual(gotResult, input.wantResult)
+	if input.wantResult != nil && gotResult != nil {
+		if ls1, ok := input.wantResult.(*ListType); ok {
+			if ls2, ok := gotResult.(*ListType); ok {
+				eq = ls1.Equals(*ls2)
+				eqDone = true
+			}
+		}
+	}
+
+	if !eqDone {
+		eq = reflect.DeepEqual(gotResult, input.wantResult)
+	}
 
 	if !eq /*gotResult != input.wantResult*/ {
 		t.Errorf("%d: `%s` -> result = %v [%s], want = %v [%s]", count, input.source, gotResult, TypeName(gotResult), input.wantResult, TypeName(input.wantResult))

t_expr_test.go

@@ -43,9 +43,11 @@ func TestExpr(t *testing.T) {
 		it++;
 		it++
 `, int64(1), nil},
+		/*  20 */ {`a=2; ${a}`, int64(2), nil},
+		/*  21 */ {`$_=2; $_`, int64(2), nil},
 	}
 	// t.Setenv("EXPR_PATH", ".")
 
-	// runTestSuiteSpec(t, section, inputs, 18)
+	// runTestSuiteSpec(t, section, inputs, 21)
 	runTestSuite(t, section, inputs)
 }

t_iter-list_test.go

@@ -59,7 +59,7 @@ func TestNewIterList2(t *testing.T) {
 
 func TestNewIterList3(t *testing.T) {
 	list := []any{"a", "b", "c", "d"}
-	it := NewAnyIterator(list)
+	it, _ := NewIterator(list)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "a" {
@@ -71,7 +71,7 @@ func TestNewIterList3(t *testing.T) {
 
 func TestNewIterList4(t *testing.T) {
 	list := any(nil)
-	it := NewAnyIterator(list)
+	it, _ := NewIterator(list)
 	if _, err := it.Next(); err != io.EOF {
 		t.Errorf("error: %v", err)
 	}
@@ -79,7 +79,7 @@ func TestNewIterList4(t *testing.T) {
 
 func TestNewIterList5(t *testing.T) {
 	list := "123"
-	it := NewAnyIterator(list)
+	it, _ := NewIterator(list)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "123" {
@@ -91,8 +91,8 @@ func TestNewIterList5(t *testing.T) {
 
 func TestNewIterList6(t *testing.T) {
 	list := newListA("a", "b", "c", "d")
-	it1 := NewAnyIterator(list)
+	it1, _ := NewIterator(list)
-	it := NewAnyIterator(it1)
+	it, _ := NewIterator(it1)
 	if item, err := it.Next(); err != nil {
 		t.Errorf("error: %v", err)
 	} else if item != "a" {
@@ -103,9 +103,9 @@ func TestNewIterList6(t *testing.T) {
 }
 func TestNewString(t *testing.T) {
 	list := "123"
-	it := NewAnyIterator(list)
+	it, _ := NewIterator(list)
-	if s := it.String(); s != "$(#1)" {
+	if s := it.String(); s != "$([#1])" {
-		t.Errorf("expected $(#1), got %s", s)
+		t.Errorf("expected $([#1]), got %s", s)
 	}
 }
 

t_iterator_test.go

@@ -31,8 +31,11 @@ func TestIteratorParser(t *testing.T) {
 		/*  20 */ {`it=$({1:"one",2:"two",3:"three"}, "default", "value"); it++`, "one", nil},
 		/*  21 */ {`it=$({1:"one",2:"two",3:"three"}, "desc", "key"); it++`, int64(3), nil},
 		/*  22 */ {`it=$({1:"one",2:"two",3:"three"}, "asc", "item"); it++`, NewList([]any{int64(1), "one"}), nil},
+		/*  23 */ {`builtin "os.file"; fileReadIterator("test-file.txt") map ${_index}`, NewList([]any{int64(0), int64(1)}), nil},
+		/*  24 */ {`builtin "os.file"; #(fileReadIterator("test-file.txt") filter (#${_} == 2))`, int64(0), nil},
+		/*  25 */ {`builtin "os.file"; #(fileReadIterator("test-file.txt") filter (#${_} == 3))`, int64(2), nil},
 	}
 
-	// runTestSuiteSpec(t, section, inputs, 20)
+	// runTestSuiteSpec(t, section, inputs, 23)
 	runTestSuite(t, section, inputs)
 }

t_operator_test.go

@@ -30,13 +30,19 @@ func TestOperator(t *testing.T) {
 		/*  17 */ {`~true`, nil, `[1:2] prefix/postfix operator "~" do not support operand 'true' [bool]`},
 		/*  18 */ {`1^2`, int64(3), nil},
 		/*  19 */ {`3^2`, int64(1), nil},
-		/*  19 */ {`a=1; a^=2`, int64(3), nil},
+		/*  20 */ {`a=1; a^=2`, int64(3), nil},
-		/*  20 */ {`a=1; ++a`, int64(2), nil},
+		/*  21 */ {`a=1; ++a`, int64(2), nil},
-		/*  21 */ {`a=1; --a`, int64(0), nil},
+		/*  22 */ {`a=1; --a`, int64(0), nil},
+		/*  23 */ {`[1,2,3] map var("_")`, newList([]any{int64(1), int64(2), int64(3)}), nil},
+		/*  24 */ {`[1,2,3] map $_`, newList([]any{int64(1), int64(2), int64(3)}), nil},
+		/*  25 */ {`[1,2,3,4] filter ($_ % 2 == 0)`, newList([]any{int64(2), int64(4)}), nil},
+		/*  26 */ {`max=0; [2,3,1] digest max=(($_ > max) ? {$_} :: {max})`, int64(3), nil},
+		/*  27 */ {`["a","b"] join ["x"]`, newList([]any{"a", "b", "x"}), nil},
+		/*  28 */ {`["a","b"] join ["x"-true]`, nil, `[1:21] left operand 'x' [string] and right operand 'true' [bool] are not compatible with operator "-"`},
 	}
 
 	// t.Setenv("EXPR_PATH", ".")
 
-	// runTestSuiteSpec(t, section, inputs, 4)
+	// runTestSuiteSpec(t, section, inputs, 28)
 	runTestSuite(t, section, inputs)
 }

t_plugin_test.go

@@ -30,9 +30,29 @@ func TestPluginExists(t *testing.T) {
 
 func TestMakePluginName(t *testing.T) {
 	name := "json"
-	want := "expr-" + name + "-plugin.so"
+	want := "expr-" + name + "-plugin" + SHAREDLIBRARY_EXTENSION
 
 	if got := makePluginName(name); got != want {
 		t.Errorf("makePluginName(%q) failed: Got: %q, Want: %q", name, got, want)
 	}
 }
+
+// func TestLoadPluginName(t *testing.T) {
+// 	name := "json"
+// 	// want := "expr-" + name + "-plugin
+// 	want := 1
+
+// 	os.Setenv("PLUGINS", "${HOME}/go/src/git.portale-stac.it/go")
+// 	// os.Setenv("EXPR_PLUGIN_PATH", "${PLUGINS}/expr-json-plugin:${PLUGINS}/expr-csv-plugin")
+// 	os.Setenv("EXPR_PLUGIN_PATH", "${PLUGINS}")
+// 	got, err := importPluginFromSearchPath(name)
+
+// 	if err != nil {
+// 		t.Errorf("importPluginFromSearchPath(%q) failed: %v", name, err)
+// 		return
+// 	}
+
+// 	if got != want {
+// 		t.Errorf("importPluginFromSearchPath(%q) failed: Got: %q, Want: %q", name, got, want)
+// 	}
+// }

t_utils-unix_test.go

@@ -0,0 +1,118 @@
+//go:build unix
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// t_utils_test.go
+package expr
+
+import (
+	"errors"
+	"os/user"
+	"path"
+	"testing"
+)
+
+func TestExpandPathRootOk(t *testing.T) {
+	source := "~root"
+	wantValue := "/root"
+	// wantErr := errors.New(`test expected string, got list ([])`)
+	wantErr := error(nil)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil && gotErr.Error() != wantErr.Error() {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestExpandPathRootSubDirOk(t *testing.T) {
+	source := "~root/test"
+	wantValue := "/root/test"
+	// wantErr := errors.New(`test expected string, got list ([])`)
+	wantErr := error(nil)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil && gotErr.Error() != wantErr.Error() {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestExpandPathUser(t *testing.T) {
+	u, _ := user.Current()
+	source := "~"
+	wantValue := path.Join("/home", u.Username)
+	// wantErr := errors.New(`test expected string, got list ([])`)
+	wantErr := error(nil)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestExpandPathEnv(t *testing.T) {
+	u, _ := user.Current()
+	source := "$HOME"
+	wantValue := path.Join("/home", u.Username)
+	// wantErr := errors.New(`test expected string, got list ([])`)
+	wantErr := error(nil)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestExpandPathErr(t *testing.T) {
+	source := "~fake-user/test"
+	wantValue := "~fake-user/test"
+	wantErr := errors.New(`user: unknown user fake-user`)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil && gotErr.Error() != wantErr.Error() {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestExpandPathUserErr(t *testing.T) {
+	u, _ := user.Current()
+	source := "~"
+	wantValue := path.Join("/home", u.Username)
+	// wantErr := errors.New(`test expected string, got list ([])`)
+	wantErr := error(nil)
+
+	gotValue, gotErr := ExpandPath(source)
+
+	if gotErr != nil {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ExpandPath(%v) gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}

t_utils_test.go

@@ -164,3 +164,48 @@ func TestCopyMap(t *testing.T) {
 		t.Errorf("utils.CopyMap() failed")
 	}
 }
+
+func TestToStringOk(t *testing.T) {
+	source := "ciao"
+	wantValue := "ciao"
+	wantErr := error(nil)
+
+	gotValue, gotErr := ToGoString(source, "test")
+
+	if gotErr != nil {
+		t.Error(gotErr)
+	} else if gotValue != wantValue {
+		t.Errorf("toGoString(%v, \"test\") gotValue=%v, gotErr=%v -> wantValue=%v, wantErr=%v",
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestToStringErr(t *testing.T) {
+	source := newListA()
+	wantValue := ""
+	wantErr := errors.New(`test expected string, got list ([])`)
+
+	gotValue, gotErr := ToGoString(source, "test")
+
+	if gotErr != nil && gotErr.Error() != wantErr.Error() {
+		t.Errorf(`ToGoString(%v, "test") gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	} else if gotValue != wantValue {
+		t.Errorf(`ToString(%v, "test") gotValue=%q, gotErr=%v -> wantValue=%q, wantErr=%v`,
+			source, gotValue, gotErr, wantValue, wantErr)
+	}
+}
+
+func TestIsFunctorSucc(t *testing.T) {
+	f := NewGolangFunctor(isNilFunc)
+	if !isFunctor(f) {
+		t.Errorf("isNilFunc() evalued as not a functor")
+	}
+}
+
+func TestIsFunctorFail(t *testing.T) {
+	f := int64(1)
+	if isFunctor(f) {
+		t.Errorf("int evalued as a functor")
+	}
+}

term.go

@@ -13,6 +13,7 @@ type termPriority uint32
 const (
 	priNone termPriority = iota
 	priRange
+	priIterOp // map, filter, digest, etc
 	priBut
 	priAssign
 	priInsert

utils-unix.go

@@ -0,0 +1,48 @@
+//go:build unix
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// utils-unix.go
+package expr
+
+import (
+	"os"
+	"os/user"
+	"path"
+	"strings"
+)
+
+func ExpandPath(sourcePath string) (expandedPath string, err error) {
+	for expandedPath = os.ExpandEnv(sourcePath); expandedPath != sourcePath; expandedPath = os.ExpandEnv(sourcePath) {
+		sourcePath = expandedPath
+	}
+
+	if strings.HasPrefix(sourcePath, "~") {
+		var home, userName, remainder string
+
+		slashPos := strings.IndexRune(sourcePath, '/')
+		if slashPos > 0 {
+			userName = sourcePath[1:slashPos]
+			remainder = sourcePath[slashPos:]
+		} else {
+			userName = sourcePath[1:]
+		}
+
+		if len(userName) == 0 {
+			home, err = os.UserHomeDir()
+			if err != nil {
+				return
+			}
+		} else {
+			var userInfo *user.User
+			userInfo, err = user.Lookup(userName)
+			if err != nil {
+				return
+			}
+			home = userInfo.HomeDir
+		}
+		expandedPath = path.Join(home, remainder)
+	}
+	return
+}

utils-windows.go

@@ -0,0 +1,18 @@
+//go:build windows
+
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// utils-unix.go
+package expr
+
+import (
+	"os"
+)
+
+func ExpandPath(sourcePath string) (expandedPath string, err error) {
+	for expandedPath = os.ExpandEnv(sourcePath); expandedPath != sourcePath; expandedPath = os.ExpandEnv(sourcePath) {
+		sourcePath = expandedPath
+	}
+	return
+}

utils.go

@@ -6,11 +6,7 @@ package expr
 
 import (
 	"fmt"
-	"os"
-	"os/user"
-	"path"
 	"reflect"
-	"strings"
 )
 
 func IsString(v any) (ok bool) {
@@ -234,37 +230,3 @@ func ForAll[T, V any](ts []T, fn func(T) V) []V {
 	}
 	return result
 }
-
-func ExpandPath(sourcePath string) (expandedPath string, err error) {
-	for expandedPath = os.ExpandEnv(sourcePath); expandedPath != sourcePath; expandedPath = os.ExpandEnv(sourcePath) {
-		sourcePath = expandedPath
-	}
-
-	if strings.HasPrefix(sourcePath, "~") {
-		var home, userName, remainder string
-
-		slashPos := strings.IndexRune(sourcePath, '/')
-		if slashPos > 0 {
-			userName = sourcePath[1:slashPos]
-			remainder = sourcePath[slashPos:]
-		} else {
-			userName = sourcePath[1:]
-		}
-
-		if len(userName) == 0 {
-			home, err = os.UserHomeDir()
-			if err != nil {
-				return
-			}
-		} else {
-			var userInfo *user.User
-			userInfo, err = user.Lookup(userName)
-			if err != nil {
-				return
-			}
-			home = userInfo.HomeDir
-		}
-		expandedPath = path.Join(home, remainder)
-	}
-	return
-}