bc and dc are probably installed on your Linux or Unix box.
By the way, you should fix "Below are some examples of sending .1 + .2 to standard output in a variety of common languages." to "[...] in a variety of languages."
It also seems like the names of bc and dc are non-capitalized.
For the Haskell entry, please just shorten it to "0.1 + 0.2". The "Prelude>" thing is just a prompt for the REPL. ":m + Data.Ratio" loads the rational number module, please take the entry about Haskell's rational numbers out since yours is a page about floating point. (You might want to replace it with a comment, that Haskell supports rational numbers. But so do lots of languages in their libraries.)
C would be a good addition. (Plus Fortran, Cobol, Ada and J.)
