Why is OP_SUBSTR disabled? (and OP_LEFT, OP_RIGHT)
Why are the substring opcodes disabled?
I perceive that OP_CAT is disabled as a result of it may blow up the stack simply (together with OP_DUP).
However the substring opcodes scale back the stack measurement.
I would like to make use of OP_LEFT to implement a proof of labor requirement to
spend a transaction. A substring operation is required as a result of OP_ADD
(for salting) and OP_GREATERTHAN solely work on 32bit values.