String comparison instead of numeric comparison is used in BtredEvaluator

[m1ch4ls]

a-node $n := [ ];
>> give lower($n.m/form)
>> filter $1 ~ '^[a-z]' 
>> for $1 give $1,count()
>> filter $2 >= 1000 
>> give $1,$2 sort by $2 desc,$1

filter $2 >= 1000 is serialized in this way: '$2 ge 1000'