Author: lwall Date: 2009-11-17 18:28:47 +0100 (Tue, 17 Nov 2009) New Revision: 29110

Modified: docs/Perl6/Spec/S02-bits.pod docs/Perl6/Spec/S09-data.pod Log: [S02,S09] break the assumption that Rats should be symmetrical Add Ratio for performance-destroying but truly arbitrary-precision rationals rename STASH to Stash for consistency Modified: docs/Perl6/Spec/S02-bits.pod =================================================================== --- docs/Perl6/Spec/S02-bits.pod 2009-11-17 16:09:39 UTC (rev 29109) +++ docs/Perl6/Spec/S02-bits.pod 2009-11-17 17:28:47 UTC (rev 29110) @@ -13,8 +13,8 @@ Created: 10 Aug 2004 - Last Modified: 09 Nov 2009 - Version: 187 + Last Modified: 17 Nov 2009 + Version: 188 This document summarizes Apocalypse 2, which covers small-scale lexical items and typological issues. (These Synopses also contain @@ -674,13 +674,23 @@ However, for pragmatic reasons, C<Rat> values are guaranteed to be exact only up to a certain point. By default, this is the precision -that would be represented by a C<rat64> type, that is, with a numerator -and denominator consisting of C<int64> values. C<Rat>s that would require -more than 64 bits of storage in either numerator or denominator are -automatically converted to C<Num>s. (If rationals are defined by a -role, it may be possible to instantiate a C<Rat> type with a different -maximum precision.) +that would be represented by the C<Rat64> type, which has a numerator +of C<Int> but is limited to a denominator of C<int64>. A C<Rat64> that +would require more than 64 bits of storage in the denominator is +automatically converted either to a C<Num> or to a lesser-precision +C<Rat>, at the discretion of the implementation. (Native types such +as C<rat64> limit the size of both numerator and denominator, though +not to the same size. The numerator should in general be twice the +size of the denominator to support user expectations. For instance, +a C<rat8> should actually support C<int16/int8>, allowing +numbers like C<100.01> to be represented, and a C<rat64>, +defined as C<int128/int64>, can hold the number of seconds since +the Big Bang with picosecond precision. Though perhaps not with +picosecond accuracy...) +For applications that really need arbitrary precision denominators +as well as numerators, C<Ratio> may be used, which is defined as C<Int/Int>. + =item * PerlĀ 6 should by default make standard IEEE floating point concepts @@ -959,6 +969,7 @@ int native signed integer uint native unsigned integer (autoboxes to Int) buf native buffer (finite seq of native ints or uints, no Unicode) + rat native rational num native floating point complex native complex number bool native boolean @@ -1073,8 +1084,9 @@ Str Perl string (finite sequence of Unicode characters) Bit Perl single bit (allows traits, aliasing, undef, etc.) Int Perl integer (allows Inf/NaN, arbitrary precision, etc.) - Num Perl number (approximate Real) - Rat Perl rational (exact Real) + Num Perl number (approximate Real, generally via floating point) + Rat Perl rational (exact Real, limited denominator) + Ratio Perl rational (unlimited precision in both parts) Complex Perl complex number Bool Perl boolean Exception Perl exception @@ -1115,7 +1127,8 @@ native TAI value. In numeric context a C<Duration> happily returns a C<Num> representing seconds. If pressed for a number, an C<Instant> will return the length of time in atomic seconds from the TAI epoch, -but it will be unhappy about it. Systems which cannot provide +but it will be unhappy about it. (The time will be returned as a C<Rat> +to preserve maximal precision and accuracy.) Systems which cannot provide a steady time base, such as POSIX systems, will simply have to make their best guess as to the correct atomic time. @@ -1128,6 +1141,7 @@ Int Numeric Integral Num Numeric Real Rat Numeric Real + Ratio Numeric Real Complex Numeric Bool Boolean Exception Failure @@ -1169,7 +1183,7 @@ Macro Perl compile-time subroutine Regex Perl pattern Match Perl match, usually produced by applying a pattern - STASH A symbol table hash (package, module, class, lexpad, etc) + Stash A symbol table hash (package, module, class, lexpad, etc) SoftRoutine A routine that is committed to staying mutable The C<KeyHash> role differs from a normal C<Associative> hash in how it handles default @@ -1231,7 +1245,7 @@ Macro Callable Regex Callable Match Positional Associative - STASH Associative + Stash Associative SoftRoutine Routine See L<S06/"Wrapping"> for a discussion of soft vs. hard routines. Modified: docs/Perl6/Spec/S09-data.pod =================================================================== --- docs/Perl6/Spec/S09-data.pod 2009-11-17 16:09:39 UTC (rev 29109) +++ docs/Perl6/Spec/S09-data.pod 2009-11-17 17:28:47 UTC (rev 29110) @@ -13,8 +13,8 @@ Created: 13 Sep 2004 - Last Modified: 21 Sep 2009 - Version: 35 + Last Modified: 17 Nov 2009 + Version: 36 =head1 Overview @@ -81,6 +81,9 @@ run-time system (presumably Parrot) is compiled in. So C<int> typically means C<int32> or C<int64>, while C<num> usually means C<num64>, and C<complex> means two of whatever C<num> turns out to be. +For symmetry around the decimal point, native rats have a numerator +that is twice the size of their denominator, such that a rat32 actually +has an int64 for its numerator. You are, of course, free to use macros or type declarations to associate additional names, such as "short" or "single". These are