Is there a way to convert a String to evaluable SAIL expression ? I

rajendray, to update my previous response in light of your previous comment about your use case, you could use eval() directly in the SAIL condition.

Hi rajendray,
According to your comments, you need a decision table (which contains set of dynamic rules like nested if conditions/multiple conditional constraints, which might be handled by end user also). So to achieve this you stored those rules in DB and try to evaluate it.
But AFAIK, you can't able to do that in Appian.

If you have fixed set of operators, comparing values also be quantifiable numbers and only one operator is used for each expression like 10>20, then you may try by splitting the expression by operator.
As your comments ,I think you don't want this.

So my suggestion is consider your requirement once and design it in Appian supported way.

correction- we can't able to do that. it won't be possible in appian

Per jackm's comments earlier, it looks like eval() might be something you can leverage to handle these. It is an undocumented function as of 7.8 at least, so Appian Best Practices (AFAIK) recommend it to be used very cautiously if at all. However, given that, I was able to test it as working in both of the code examples you posted earlier. What's more, you can push a value into a local variable and then evaluate text containing that local variable.
i.e.

=load(
local!value: "asdf",
eval(
"len(local!value)=4"
)
)

Thanks all ,eval() did the trick for me.

BEWARE! This is an unsupported function.