edits

concepts/more-arrays/introduction.md

@@ -7,7 +7,7 @@ This document will show more ways to use arrays.
 
 In the previous Arrays chapter, you saw `"${myarray[@]}"`, with the `@` index, to expand the array into the individual elements.
 But sometimes you want to join all the elements into a single string.
-For this, use the `*` index: 
+For this, use the `*` index:
 
 ```bash
 echo "${myarray[*]}"
@@ -18,12 +18,11 @@ You are required to enclose the expansion in double quotes.
 Bash uses the _first character_ of the `IFS` builtin variable as the separator character.
 By default, `$IFS` consists of space, tab and newline.
 
-This demo shows that the `mystring` variable contains "one two three four".
-
 ```bash
 myarray=(one two three four)
 mystring="${myarray[*]}"
 declare -p mystring
+# => declare -- mystring="one two three four"
 ```
 
 We can manipulate the `IFS` variable to use a different separator character:
@@ -33,13 +32,11 @@ myarray=(one two three four)
 IFS=","
 mystring="${myarray[*]}"
 declare -p mystring
+# => declare -- mystring="one,two,three,four"
 ```
 
-Now, `mystring` contains "one,two,three,four".
-
 ~~~~exercism/advanced
 We can encapsulate this into a function.
-This will output "one:two:three:four".
 
 ```bash
 join() {
@@ -50,11 +47,12 @@ join() {
 }
 
 join ":" "${myarray[@]}"     # note, the "@" index
+# => "one:two:three:four"
 ```
 
-Using a local variable in a function means we don't have restore IFS back to it's previous value.
+Localizing `IFS` in the function means we don't have to save the old value and restore it back to it's previous value in the global scope.
 
-As a refinement, the special parameter `"$*"` has the same functionality here, so we don't need to save a copy of the function's arguments:
+As a refinement, the special parameter `"$*"`, when quoted, has the same functionality so we don't need to save a copy of the function's arguments:
 
 ```bash
 join() {
@@ -78,7 +76,11 @@ declare -p subarray         # => subarray=([0]="one" [1]="two")
 
 subarray=("${myarray[@]:1:3}")
 declare -p subarray         # => subarray=([0]="two" [1]="three" [2]="four")
+```
+
+Omitting the length part means "from the offset to the end of the array":
 
+```bash
 subarray=("${myarray[@]:2}")
 declare -p subarray         # => subarray=([0]="three" [1]="four")
 ```
@@ -90,7 +92,7 @@ There are 3 techniques to pass an array to a function, and only one of them allo
 
 ### Pass the Elements
 
-You can just pass the array's values, and collect them in the function.
+In the first technique, you just pass the array's values and collect them into a local array in the function.
 
 ```bash
 myfunc() {
@@ -114,8 +116,8 @@ For these two techniques, you pass the array _name_ as a string.
 
 Suppose you have variable `x=5` and variable `y=x`, and you want to use the `y` variable to get the value `5`.
 Some other languages let you do `$$y` but not Bash.
-Bash has a technique called "indirect expansion" (described in the manual in [Shell Parameter Expansion][parameter-expansion]).
-In bash, this uses the `!` in a different way than we have seen before:
+Bash has a technique called **indirect expansion** (described in the manual in [Shell Parameter Expansion][parameter-expansion]).
+In bash, this uses the `!` character in a different way than we have seen before:
 
 ```bash
 x=5
@@ -138,6 +140,7 @@ array_original=(11 22 33 44)
 myfunc "array_original"
 ```
 
+This technique is quite messy.
 The `temp` variable will contain the _string `"array_original[@]"`.
 Then the indirect expansion expands to the global array's values.
 
@@ -183,9 +186,12 @@ myfunc() {
     local IFS=,
     echo "${a[*]}"
 }
+
+# same name as the function's local variable
 a=(one two three)
 myfunc a
 ```
+
 ```none
 bash: local: warning: a: circular name reference
 bash: warning: a: circular name reference
@@ -216,5 +222,7 @@ for item in "$@"; do
 done
 ```
 
+If your goal is to write "portable" shell scripts, you'll use the positional parameters to store a "list" of values.
+
 [arrays]: https://exercism.org/tracks/bash/concepts/arrays
 [parameter-expansion]: https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameter-Expansion