[RFC PATCH 02/28] cli: Add LIL shell

[Sean Anderson]

On 7/5/21 3:10 PM, Tom Rini wrote:
> On Sat, Jul 03, 2021 at 09:33:30PM +0200, Wolfgang Denk wrote:
>> Dear Sean,
>>
>> In message <8bbdb7a1-5085-a3b7-614f-12ae9aee8e8b at gmail.com> you wrote:
>>>
>>>> For a partial list, see
>>>>
>>>> [1] https://github.com/Forty-Bot/lil/commits/master
>>>
>>> Whoops, looks like I completely misread what you were asking here. I
>>> don't have an exhaustive list of differences, but here are some similar
>>> things expressed in both languages:
>>>
>>> sh				tcl
>>>
>>> foo=bar				set foo bar
>>> echo $foo			echo $foo
>>>
>>> if [ 1 -gt 2 ]; then		if {1 > 2} {
>>> 	echo a				echo a
>>> else				} {
>>> 	echo b				echo b
>>> fi				}

The left side is possible with something like

if itest 1 -gt 2; then # etc.

>>>
>>> foo() {				proc foo {first second} {
>>> 	echo $1 $2			echo $first $second
>>> }				}

This is not possible. We only have eval (run) as of today. I view adding
functions as one of the most important usability improvements we can
make.

>>>
>>> for file in $(ls *.c); do	foreach file [glob *.c] {
>>> 	echo $file			echo $file
>>> done				}

This is possible only if you already have a list of files. For example,
one could do

part list mmc 0 -bootable parts
for p in $parts; do #etc

but the part command is one of the only ones which produces output in
the correct format. If you want to (e.g.) dynamically construct a list
you will have a much harder time.

>>> fact() {
>>> 	if [ $1 -eq 0 ]; then
>>> 		echo 1
>>> 	else
>>> 		echo $(($1 * $(fact $(($1 - 1)))))
>>> 	fi
>>> }

This is technically possible with run and setexpr, but fairly cumbersome
to do.

>>>
>>> 				proc fact {n} {
>>> 					if {$n} {
>>> 						expr {$n * [fact [expr {$n - 1}]]}
>>> 					} {
>>> 						return 1
>>> 					}
>>> 				}
>>>
>>> Hopefully this gives you a bit of a feel for the basic differences.
> 
> Which of these things, from each column, can you do in the context of
> U-Boot?  That's important too.

See above.

--Sean