notes.txt

Profiling:

    - The program was throwing Stack Overflows during the quick-checks.
    - To diagnose these I wished to compile the tests with profiling activated.
    - This required the use of '-prof' and '-fprof-auto' flags in the 'ghc make' command.
    - This command failed because profiling wasn't enabled in ghc as well as in any of the other packages being used.

To Enable Profiling:

    - sudo apt-get install ghc-prof         # A variant of ghc with profiling enabled. This provides the 'base' module (which includes Prelude) with profiling
    - To upgrade any Haskell package to use profiling issue: sudo cabal install -p <package> --reinstall
    - If any of the dependencies of the package doesn't have profiling enabled then this command will fail and one will have to reinstall the dependency (with profiling enabled) first.

    - To insist that cabal install all libraries with profiling enabled edit ~/.cabal/config and add the line 'library-profiling: True' (uncomment the default False valued line and change it)



To-Do:

    - Automate the rule that Sum [] = Const 0 (sum over zero elements is equal to zero - the additive identity)
    - Automate the rule that Sum [e] = e (sum over single element is the element itself)

    - Investigate making Sum [list] behave like a list that is treat Sum as a concatenation of Expr elements e1:e2:e3:[]. This will greatly simplify pattern matching

    - Possibly use "View Patterns" to implement pattern matching complicated by the large number of constructors for Expr
    - Possibly consolidate Sum and Prod in to a single type with two constructors of its own. This will consolidate their similarities.

    - Some good ideas on CAS as a DSL: http://tom.lokhorst.eu/2009/09/deeply-embedded-dsls