It's a well known fact that programs with immutable objects much easy to maintain, test and use, but the main benefit form immutable objects is that they allow performing more aggressive optimizations [1] and apply more valuable analysis. DeMu is exactly the tool for removing mutable objects like memory and cage from EO programs. Actually, DeMu is acronym for De-Muatabilization.

There isn't single formal methodology or algorithm for converting mutable objects into immutable, but we can use some separate methods to achieve this.

We actually can apply SSA [2] form for eo programs. This approach can immediately remove some usages of mutable objects. Let's consider the following example:

[] > example
  cage 0 > index
  seq > @
    index.write 1
    stdout
      sprintf
        "%s"
        index
    TRUE

After applying SSA form we get something like the next:

[] > example
  seq > @
    stdout
      sprintf
        "%s"
        1
    TRUE

And as you can see - we removed usage of cage from the result program. The relation between SSA form and Dataflow Languages (like EO and, particularly, Functional Programming Languages) is quite well described in that article [3].

The second method is to convert loops into recursive calls.

1. Immutability specification and its applications
2. Global Value Numbers and Redundant Computations
3. SSA is Functional Programming

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