diff options
| -rw-r--r-- | lib.c | 21 | ||||
| -rw-r--r-- | txr.1 | 67 |
2 files changed, 82 insertions, 6 deletions
@@ -4731,7 +4731,26 @@ tail: case NIL: return str_lt(nil_string, symbol_name(right)); case SYM: - return str_lt(left->s.name, symbol_name(right)); + { + val cmp = cmp_str(left->s.name, symbol_name(right)); + if (cmp == negone) { + return t; + } else if (cmp == one) { + return nil; + } else { + val lpkg = left->s.package; + val rpkg = right->s.package; + + if (lpkg == nil && rpkg == nil) + return tnil(left < right); + if (lpkg == nil) + return t; + if (rpkg == nil) + return nil; + + return str_lt(lpkg->pk.name, rpkg->pk.name); + } + } case CONS: case LCONS: for (;;) { @@ -18251,6 +18251,42 @@ even if the function doesn't handle comparing different instances of that type. In other words, no object is less than itself, no matter what it is. +The +.code less +function pairs with the +.code equal +function. If values +.code a +and +.code b +are objects which are of suitable types to the +.code less +function, then exactly one of the following three expressions must be true: +.codn "(equal a b)" , +.code "(less a b)" +or +.codn "(less b a)" . + +The +.code less +relation is: antisymmetric, such that if +.code "(less a b)" +is true, then +then +.code "(less b a)" +is false; irreflexive, such that +.code "(less a a)" +is false; and transitive, such that +.code "(less a b)" +and +.code "(less b c)" +imply +.codn "(less a c)" . + +The following are detailed criteria that +.code less +applies to arguments of different types and combinations thereof. + If both arguments are numbers or characters, they are compared as if using the .code < function. @@ -18259,10 +18295,31 @@ If both arguments are strings, they are compared as if using the .code string-lt function. -If both arguments are symbols, then their names are compared in -their place, as if by the +If both arguments are symbols, the following rules apply. +If the symbols have names which are different, then the result is +that of their names being compared by the .code string-lt -function. +function. If +.code less +is passed symbols which have the same name, and neither of these +symbols has a home package, then the raw bit patterns of their +values are compared as integers: effectively, the object with the +lower machine address is considered lesser than the other. +If only one of the two same-named symbols has no home package, then if +that symbol is the left argument, +.code less +returns +.codn t , +otherwise +.codn nil . +If both same-named symbols have home packages, then the result of +.code less +is that of +.code string-lt +applied to the names of their respective packages. Thus +.code a:foo +is less than +.codn z:foo . If both arguments are conses, then they are compared as follows: .RS @@ -18352,8 +18409,8 @@ is applied to the .code to fields and that result is returned. -If the two arguments are of the above types, but of mutually different types, -then +If the two arguments are of the above types, but of different types from +each other, then .code less resolves the situation based on the following precedence: numbers and characters are less than ranges, which are less than strings, which are less |