Revision 27106

Date:
2009/06/17 19:08:15
Author:
lwall
Revision Log:
[S02] define utf constrained buffer types
[S02] nail down canonical name for instantiated types to use ident adverbial
(MyRole[MyType] still instantiates, but isn't the name of the resulting type)
Files:

Legend:

 
Added
 
Removed
 
Modified

  • docs/Perl6/Spec/S02-bits.pod

     
    12 12
    13 13 Maintainer: Larry Wall <larry@wall.org>
    14 14 Date: 10 Aug 2004
    15 Last Modified: 2 Jun 2009
    16 Version: 170
    15 Last Modified: 17 Jun 2009
    16 Version: 171
    17 17
    18 18 This document summarizes Apocalypse 2, which covers small-scale
    19 19 lexical items and typological issues. (These Synopses also contain
    … …  
    464 464 name" of the resulting type, so one C<Array of Int> is equivalent to
    465 465 another C<Array of Int>. (Another way to look at it is that the type
    466 466 instantiation "factory" is memoized.) Typename aliases are considered
    467 equivalent to the original type.
    467 equivalent to the original type. In particular, the C<Array of Int> syntax
    468 is just sugar for C<Array:of(Int)>, which is the canonical form of an
    469 instantiated generic type.
    468 470
    469 471 This name equivalence of parametric types extends only to parameters
    470 472 that can be considered immutable (or that at least can have an
    … …  
    800 802
    801 803 =item *
    802 804
    805 The C<utf8> type is derived from C<buf8>, with the additional constraint
    806 that it may only contain validly encoded UTF-8. Likewise, C<utf16> is
    807 derived from C<buf16>, and C<utf32> from C<buf32>.
    808
    809 Note that since these are type names, parentheses must always be
    810 used to call them as coercers, since the listop form is not allowed
    811 for coercions. That is:
    812
    813 utf8 op $x
    814
    815 is always parsed as
    816
    817 (utf8) op $x
    818
    819 and never as
    820
    821 utf8(op $x)
    822
    823 =item *
    824
    803 825 The C<*> character as a standalone term captures the notion of
    804 826 "Whatever", which is applied lazily by whatever operator it is an
    805 827 argument to. Generally it can just be thought of as a "glob" that
    … …  
    1163 1185
    1164 1186 actually means:
    1165 1187
    1166 my Hash[Array[Recipe]] %book;
    1188 my Hash:of(Array:of(Recipe)) %book;
    1167 1189
    1168 1190 Because the actual variable can be hard to find when complex types are
    1169 1191 specified, there is a postfix form as well:
    … …  
    1215 1237 my Cat|Dog Fish $mitsy = new Fish but { Bool.pick ?? .does Cat
    1216 1238 !! .does Dog };
    1217 1239
    1240 [Note: the above is a slight lie, insofar as parameters are currently
    1241 restricted for 6.0.0 to having only a single main type for the
    1242 formal variable until we understand MMD a bit better.]
    1243
    1218 1244 =head2 Parameter types
    1219 1245
    1220 1246 Parameters may be given types, just like any other variable: