I haven't read the book but the snapshot is definitely Haskell. Most texts that contain Haskell code use some kind of pretty printer, most likely lhs2TeX. It assigns more type-setting-friendly symbols to many standard Haskell infix operations such as ++ or <=.
I suggest you to use browse Haskell's Prelude module, which contains functions available to all Haskell programs by default. Or you can search for a particular function using Hoogle.