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@@ -16795,7 +16795,7 @@ involves manipulating tagged values, the representation must be
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efficient. Recall that all of our values are 64 bits. We shall steal
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efficient. Recall that all of our values are 64 bits. We shall steal
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the 3 right-most bits to encode the tag. We use $001$ to identify
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the 3 right-most bits to encode the tag. We use $001$ to identify
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integers, $100$ for Booleans, $010$ for vectors, $011$ for procedures,
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integers, $100$ for Booleans, $010$ for vectors, $011$ for procedures,
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-and $101$ for the void value. We define the following auxiliary
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+and $101$ for the void value\python{, \key{None}}. We define the following auxiliary
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function for mapping types to tag codes.
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function for mapping types to tag codes.
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{\if\edition\racketEd
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{\if\edition\racketEd
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\begin{align*}
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\begin{align*}
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@@ -16815,8 +16815,8 @@ function for mapping types to tag codes.
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\itm{tagof}(\key{type(None)}) &= 101
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\itm{tagof}(\key{type(None)}) &= 101
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\end{align*}
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\end{align*}
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\fi}
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\fi}
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-This stealing of 3 bits comes at some price: our integers are reduced
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-to ranging from $-2^{60}$ to $2^{60}$. The stealing does not adversely
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+This stealing of 3 bits comes at some price: integers are now restricted
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+to the range from $-2^{60}$ to $2^{60}$. The stealing does not adversely
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affect vectors and procedures because those values are addresses, and
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affect vectors and procedures because those values are addresses, and
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our addresses are 8-byte aligned so the rightmost 3 bits are unused,
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our addresses are 8-byte aligned so the rightmost 3 bits are unused,
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they are always $000$. Thus, we do not lose information by overwriting
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they are always $000$. Thus, we do not lose information by overwriting
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@@ -16931,7 +16931,8 @@ Note that in both \code{Inject} and \code{Project}, the type $T$ is
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restricted to a flat type $\FType$, which simplifies the
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restricted to a flat type $\FType$, which simplifies the
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implementation and corresponds with the needs for compiling \LangDyn{}.
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implementation and corresponds with the needs for compiling \LangDyn{}.
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-The \racket{\code{any-vector}}\python{\code{any\_tuple}} operators
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+The \racket{\code{any-vector}} operators
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+\python{\code{any\_tuple\_load} and \code{any\_len}}
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adapt the tuple operations so that they can be applied to a value of
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adapt the tuple operations so that they can be applied to a value of
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type \racket{\code{Any}}\python{\code{AnyType}}. They also generalize the
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type \racket{\code{Any}}\python{\code{AnyType}}. They also generalize the
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tuple operations in that the index is not restricted to be a literal
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tuple operations in that the index is not restricted to be a literal
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@@ -18098,7 +18099,7 @@ not a tuple. We enable this differentiation by choosing not to use the
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tag $000$ in the $\itm{tagof}$ function. Instead, that bit pattern is
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tag $000$ in the $\itm{tagof}$ function. Instead, that bit pattern is
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reserved for identifying plain old pointers to tuples. That way, if
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reserved for identifying plain old pointers to tuples. That way, if
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one of the first three bits is set, then we have a tagged value and
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one of the first three bits is set, then we have a tagged value and
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-inspecting the tag can differentiation between tuples ($010$) and the
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+inspecting the tag can differentiate between tuples ($010$) and the
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other kinds of values.
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other kinds of values.
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%% \begin{exercise}\normalfont
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%% \begin{exercise}\normalfont
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Peter Thiemann