[julia-users] Evaluation of boolean expression fails

[Ali Rezaee]

Hi everyone,

I am trying to run the code below. When I try the code outside of a 
function and in REPL, it runs successfully. However when I run it using a 
function it throw an error.
Why do I get the error? and how can I solve this problem?

Thanks in advance for your help.

rules = ["(x[1] && x[2])", "(x[3] || x[4])"]; # a list of boolean 
expressions
boolList = [false, true, false, true]; # a boolean vector for every x in 
rules

function evaluate(rules, boolList)
  x = boolList
  result = Array{Bool}(length(rules))
  for (i, rule) in enumerate(rules)
    result[i] = eval(parse(rule))
  end
  return result
end

evaluate(rules, boolList)
# ERROR: UndefVarError: x not defined

# but This will work:
x = boolList
result = Array{Bool}(length(rules))
for (i, rule) in enumerate(rules)
  result[i] = eval(parse(rule))
end

result
# 2-element Array{Bool,1}: false true