I just saw this on the OCaml list (in a posting by "Rafael 'Dido'
Sevilla"
2. Haskell strings are lists of characters
It's annoying that strings aren't normally processed this way in OCaml, and even more annoying that (^) or (::) cannot be used in pattern matching over strings. I like Haskell's approach. The list concatenation operator is the same as the string concatenation operator in Haskell.
This is something of an efficiency/elegance tradeoff. Making strings act like lists means potentially boxing *every character in the string*. In other words, it's potentially a very expensive way of doing business. Paul Graham was mulling over this kind of tradeoff in his design of Arc, as I recall. Another language that does this type of thing is Erlang, and both languages seem to be significantly slower than OCaml in string handling, at least as far as this site goes:
http://shootout.alioth.debian.org/
For the word count benchmark OCaml scores 0.1850 seconds, while GHC is a dismal last place at 105.2110 seconds! Even the bytecode ocaml is an order of magnitude faster. The word frequency benchmark also shows this kind of poor string handling performance for Haskell, with OCaml scoring 0.5669 seconds, while GHC scores a truly dismal 6.4540, more than an order of magnitude slower, and even the bytecode ocaml is faster at 4.2644 seconds.
All in all, it would appear that Haskell's approach has been expensive in terms of performance, if the benchmarks are to be taken at face value. Such are the tradeoffs language designers have to make.