On Tue, Oct 9, 2012 at 3:42 PM, archisman rudra archi.rudra@gmail.com wrote:

My confusion is whether it matters that 2147483648 < 1234567898723618080928927362387

Doesn't the type descriptor (INTEGER 2147483648) mean integers upto 2147483648?

No, it means integers > 2147483648

it is (integer low &optional high)

-Alan

Thanks, that was my error. This flurry of emails made me go look at the hyperspec.

On Tue, Oct 9, 2012 at 3:48 PM, Zach Beane xach@xach.com wrote:

archisman rudra archi.rudra@gmail.com writes:

...

My confusion is whether it matters that 2147483648 < 1234567898723618080928927362387

Doesn't the type descriptor (INTEGER 2147483648) mean integers upto

2147483648?

No, the INTEGER type specifier takes two arguments. The first one expresses the lower bound, and the optional second the upper bound. If the second argument is omitted, it defaults to *, meaning no upper bound.

(MOD 2147483648) is more what you're thinking of.

Zach

Ah, I see. There is freedom on the part of implementations here.

thanks

On Tue, Oct 9, 2012 at 3:36 PM, Alan Ruttenberg alanruttenberg@gmail.comwrote:

On Tue, Oct 9, 2012 at 2:34 PM, archisman rudra archi.rudra@gmail.comwrote:

...

Is this correct behavior?

CL-USER(17): (type-of 1234567898723618080928927362387) (INTEGER 2147483648)

The relevant java code is in Bignum.java: (the value field is a java BigInteger)

@Override public LispObject typeOf() { if (value.signum() > 0) return list(Symbol.INTEGER, new Bignum((long)Integer.MAX_VALUE + 1)); return Symbol.BIGNUM; }

for comparison: CL-USER(23): (type-of -1234567898723618080928927362387) BIGNUM

which makes intuitive sense.

http://www.lispworks.com/documentation/lw51/CLHS/Body/f_tp_of.htm

*Relevant bits of type-of description:*

Returns a *type specifier*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#type_specifier , *typespec*, for a *type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#type that has the *object* as an *element*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_e.htm#element. The *typespec* satisfies the following:

1. For any *object* that is an *element*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_e.htm#element of

some *built-in type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_b.htm#built-in_type :

a. the *type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#type returned is a *recognizable subtype*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_r.htm#recognizable_subtype of that *built-in type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_b.htm#built-in_type .

b. the *type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#type returned does not involve and, eql, member, not, or, satisfies, or values.

3. The *type*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#type returned

by *type-of*http://www.lispworks.com/documentation/lw51/CLHS/Body/f_tp_of.htm#type-of is always a *recognizable subtype*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_r.htm#recognizable_subtype of the *class*http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_c.htm#class returned by *class-of*http://www.lispworks.com/documentation/lw51/CLHS/Body/f_clas_1.htm#class-of. That is,

(subtypep (type-of object) (class-of object)) => true http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#true, true http://www.lispworks.com/documentation/lw51/CLHS/Body/26_glo_t.htm#true

So my read is that there's no guarantee of literal repeatability between the returned values of type-of even in subsequent calls, never mind between implementations.

-Alan

...

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