Re: Assigning a plane for mapping digits for many different bases

From: Hans Aberg (
Date: Wed Mar 09 2011 - 10:51:46 CST

  • Next message: Hans Aberg: "Re: Assigning a plane for mapping digits for many different bases"

    On 9 Mar 2011, at 16:24, Philippe Verdy wrote:

    > No such ambiguity : List separators, if they use a comma, should
    > follow it by a space.
    > So "1,2" is unambiguously NOT a list of two numbers, but a single
    > number; "1, 2" is interpreted exactly the reverse way.

    Yes, but for example the Haskell interactive compiler GHCi and interpreter Hugs write lists without a comma. So if one gets used to that, it may produce a nasty surprise.

    Examples like these are called "gotchas", that is, even though it work as documented, it is contrary to human expectation.

    > In technical papers or articles or user guides, intended to be read by
    > humans, the locale used in the document will apply simultaneously to
    > number formats and list formats.
    > But within locales that use the comma as a decimal separator,
    > preferably use the semi-colon as the list separator for technical data
    > files (for example, CSV files saved and parsed by the French
    > localization of Excel, with the defautl settings), because the space
    > is ignored and used instead as optional padding. For such technical
    > data files, the comma should never be used as a value separator in
    > lists (other commonly used list separators are the pipe character (|)
    > and the colon in many Unix settings files)

    These days, one cannot expect a single, consistent use. Whence declaration the 2003 by the 22nd General Conference on Weights and Measures.

    > No ambiguity also within most programming languages (because numeric
    > constants are not localizable and use a single syntax, and list of
    > values are used for lots of things and almost always use the comma,
    > for example in function/method parameters, initializers, declarators,
    > enumerations).
    > 2011/3/9 Hans Aberg <>:
    >> On 9 Mar 2011, at 12:56, André Szabolcs Szelp wrote:
    >>>> Dots are also used for IPv4, but it becomes ambiguous if one needs a fractional part.
    >>> Oh, quite a lot of people use "," for fractional parts...
    >> The 22nd General Conference on Weights and Measures (2003) declared to use either a "." or a "," (see page below, section "History", last paragraph). Admitting both though creates an ambiguity of 1,2 interpreted as a list of two numbers 1, 2 or a single number 1.2.

    This archive was generated by hypermail 2.1.5 : Wed Mar 09 2011 - 10:54:28 CST