use generics for contains() and add generic exists()

fix pod formatting (fixes #24)

calc.go

@@ -261,7 +261,7 @@ func (c *Calc) Eval(line string) {
 				continue
 			}
 
-			if _, ok := c.Funcalls[item]; ok {
+			if exists(c.Funcalls, item) {
 				if err := c.DoFuncall(item); err != nil {
 					fmt.Println(err)
 				} else {
@@ -270,8 +270,12 @@ func (c *Calc) Eval(line string) {
 				continue
 			}
 
-			if c.batch {
-				if _, ok := c.BatchFuncalls[item]; ok {
+			if exists(c.BatchFuncalls, item) {
+				if !c.batch {
+					fmt.Println("only supported in batch mode")
+					continue
+				}
+
 				if err := c.DoFuncall(item); err != nil {
 					fmt.Println(err)
 				} else {
@@ -279,12 +283,6 @@ func (c *Calc) Eval(line string) {
 				}
 				continue
 			}
-			} else {
-				if _, ok := c.BatchFuncalls[item]; ok {
-					fmt.Println("only supported in batch mode")
-					continue
-				}
-			}
 
 			if contains(c.LuaFunctions, item) {
 				// user provided custom lua functions
@@ -304,22 +302,22 @@ func (c *Calc) Eval(line string) {
 			}
 
 			// internal commands
-			if _, ok := c.Commands[item]; ok {
+			if exists(c.Commands, item) {
 				c.Commands[item].Func(c)
 				continue
 			}
 
-			if _, ok := c.ShowCommands[item]; ok {
+			if exists(c.ShowCommands, item) {
 				c.ShowCommands[item].Func(c)
 				continue
 			}
 
-			if _, ok := c.StackCommands[item]; ok {
+			if exists(c.StackCommands, item) {
 				c.StackCommands[item].Func(c)
 				continue
 			}
 
-			if _, ok := c.SettingsCommands[item]; ok {
+			if exists(c.SettingsCommands, item) {
 				c.SettingsCommands[item].Func(c)
 				continue
 			}
@@ -507,7 +505,7 @@ func (c *Calc) PutVar(name string) {
 }
 
 func (c *Calc) GetVar(name string) {
-	if _, ok := c.Vars[name]; ok {
+	if exists(c.Vars, name) {
 		c.Debug(fmt.Sprintf("retrieve %.2f from %s", c.Vars[name], name))
 		c.stack.Backup()
 		c.stack.Push(c.Vars[name])

rpn.go

@@ -178,17 +178,27 @@ DESCRIPTION
         [no]debug            toggle debug output (nodebug turns it off)
         [no]showstack        show the last 5 items of the stack (noshowtack turns it off)
 
-    Show commands: dump display the stack contents hex show last stack item
-    in hex form (converted to int) history display calculation history vars
-    show list of variables
+    Show commands:
 
-    Stack manipulation commands: clear clear the whole stack shift remove
-    the last element of the stack reverse reverse the stack elements swap
-    exchange the last two stack elements dup duplicate last stack item undo
-    undo last operation edit edit the stack interactively using vi or
-    $EDITOR
+        dump                 display the stack contents
+        hex                  show last stack item in hex form (converted to int)
+        history              display calculation history
+        vars                 show list of variables
 
-    Other commands: help|? show this message manual show manual
+    Stack manipulation commands:
+
+        clear                clear the whole stack
+        shift                remove the last element of the stack
+        reverse              reverse the stack elements
+        swap                 exchange the last two stack elements
+        dup                  duplicate last stack item
+        undo                 undo last operation
+        edit                 edit the stack interactively using vi or $EDITOR
+
+    Other commands:
+
+        help|?               show this message
+        manual               show manual
         quit|exit|c-d|c-c    exit program
 
     Register variables:

rpn.pod

@@ -186,12 +186,14 @@ Configuration Commands:
     [no]showstack        show the last 5 items of the stack (noshowtack turns it off)
 
 Show commands:
+
     dump                 display the stack contents
     hex                  show last stack item in hex form (converted to int)
     history              display calculation history
     vars                 show list of variables
 
 Stack manipulation commands:
+
     clear                clear the whole stack
     shift                remove the last element of the stack
     reverse              reverse the stack elements
@@ -201,6 +203,7 @@ Stack manipulation commands:
     edit                 edit the stack interactively using vi or $EDITOR
 
 Other commands:
+
     help|?               show this message
     manual               show manual
     quit|exit|c-d|c-c    exit program

util.go

@@ -23,16 +23,24 @@ import (
 	"strings"
 )
 
-// find an item in a list
-func contains(s []string, e string) bool {
-	for _, a := range s {
-		if a == e {
+// find an item in a list, generic variant
+func contains[E comparable](s []E, v E) bool {
+	for _, vs := range s {
+		if v == vs {
 			return true
 		}
 	}
 	return false
 }
 
+// look if a key in a map exists, generic variant
+func exists[K comparable, V any](m map[K]V, v K) bool {
+	if _, ok := m[v]; ok {
+		return true
+	}
+	return false
+}
+
 func const2num(name string) float64 {
 	switch name {
 	case "Pi":