eval to support math comparison

[sagiegurari]

No description provided.

[ModProg]

not sure what this would involve, but one feature that could fit in here is fish like command evaluation for inputs to other commands

so e.g. this could be supported:

if less_than (get_last_modified_time package.lock) (current_time)
    echo hi
end

[sagiegurari]

you have calc + less/greater/eq commands.
isn't it working for your use case?

[ModProg]

It might just be that I'm not very experienced with duckscript, but this got rather lengthy.

package_lock_modified = get_last_modified_time yarn.lock 
current_time = current_time
current_time = calc ${current_time} - 48*60*60*1000
less_than_two_days_old = less_than ${package_lock_modified} ${current_time} 
package_json_newer = is_path_newer package.json yarn.lock
if ${less_than_two_days_old} or ${package_json_newer}
    exec --fail-on-error yarn
    exec touch yarn.lock
else
    echo "Packages up to date"
end

I would have prefered to be able to do something like this:

if (less_than 
        (get_last_modified_time yarn.lock)
        (calc (current_time) - 48*60*60*1000)) 
    or (is_path_newer package.json yarn.lock)
    exec --fail-on-error yarn
    exec touch yarn.lock
else
    echo "Packages up to date"
end

[sagiegurari]

ya the conditions are a bit basic in their capabilities and duckscript in general has 1 command per 1 line rule.
also per the format of output=command args this one: calc (current_time) - 486060*1000 will probably never be implemented.

[ModProg]

calc (current_time) - 48*60*60*1000 will probably never be implemented.

Makes sense. I just thought it might be a useful feature to basically have a shortcut to always needing to move everything in a variable.

Fish follows a similar approach, wanting to have a simple syntax that prefers e.g. commands over language features, that's why I proposed their syntax.

Thinking about it, maybe something more inline with the variable expansions $(...) would maybe make more sense and also lowers the risk of accidentally triggering it.

It should also not increase the implementation complexity too much, as the implementation could basically be:

1. Find $(inner)
2. Replace it with ${var_name}
3. Introduce new variable in line above var_name = inner

Probably makes not a lot of sense to actually implement it like that, but I would find it quite useful.

[sagiegurari]

can you explain a bit more? maybe put some small example?

[ModProg]

can you explain a bit more? maybe put some small example?

Basically my example from above.

A bit simplified, this:

if less_than $(get_last_modified_time file) $(calc $(current_time) - 100)
    echo true
else
    echo false
end

Should internally expand to

__get_last_modified_time = get_last_modified_time file
__current_time = current_time
__calc = calc ${__current_time} - 100
if less_than ${__get_last_modified_time} ${__calc}
    echo true
else
    echo false
end

I used __ to mark internal variables. But they probably don't even need names.