On 7 Oct 2011, at 22:29, Asmus Freytag wrote: > Murray's work comes from the desire to represent mathematical equations > faithfully, based nearly entirely on the semantics of the operators and > having those operators be represented as Unicode characters. > > One solution that he uses is the use of "redundant" parens. Parens can be > supplied to group operands, so that you get the correct precedence, but, > where they are not necessary to the human reader, they will be dropped in the > formatted equation. > > As input format, the linear format, therefore looks more like current source > code, in that one does type parens. > > When fractions are built up, you don't need the parens, so they are dropped > in layout. If you take the same fraction and display it inline (with a slash) > some or all of the parens would be needed for the human reader as well, so > those are displayed. > > How would you parse 5.5 if input as a fraction? 51/2? You do need some form > of grouping to recognize that the 5 and the 1 are not part of the same > numerator.
Apart from that I treat as 5.5 as an inexact number, distinct from the exact rational numbers, I use right now "5 1/2", requiring there to be exactly one space, where the "/" can also be a ⁄ U+2044 FRACTION SLASH. Expressions like "f x" parse as function application "f(x)", which is popular now in functional languages such as Haskell. So in principle, "5 1/2" might parse as "5(1/2)", the constant function 5 applied to 1/2. Hans
