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NEWS: Add more text.

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* NEWS: Update.
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Mark H Weaver 2019-06-18 13:53:56 -04:00
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NEWS
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@ -10,17 +10,36 @@ Changes in 2.2.5 (since 2.2.4):
[XXX TODO: Add more details to selected items below]
* Notable changes
* Notable improvements
** Greatly improved performance of bidirectional pipes.
The performance of bidirectional pipes, as created using 'open-pipe' or
'open-pipe*' with OPEN_BOTH mode, has been improved by roughly 3 orders
of magnitude.
'open-pipe*' in OPEN_BOTH mode, has been greatly improved. When reading
large blocks of binary data from a bidirectional pipe, the maximum
bandwidth has been increased by a factor of ~10^3 in some cases.
** New 'get-bytevector-some!' I/O primitive.
** get-bytevector-{some,some!,n!} support suspendable I/O.
This new I/O primitive is similar to 'get-bytevector-some' from the
R6RS, except that it writes its data to a user-specified range of
indices in an existing bytevector. As a corollary, it is also now
possible to specify a maximum number of bytes to read. Note that
'get-bytevector-some', and now 'get-bytevector-some!', are unique among
Guile's I/O primitives in their support of efficient binary reads of
potentially large blocks while also allowing for short reads, to avoid
undesired blocking. Now these operations can be performed while also
avoiding heap-allocation.
'get-bytevector-some!' is needed to efficiently implement the new
bidirectional pipes, which are built upon R6RS custom binary
input/output ports.
** get-bytevector-{n!,some,some!} now support suspendable I/O.
Scheme implementations of 'get-bytevector-n!', 'get-bytevector-some',
and 'get-bytevector-some!' have been added to (ice-9 suspendable-ports).
As a result, these I/O operations now support suspendable I/O.
* Compiler improvements
@ -35,8 +54,26 @@ eval.go and psyntax-pp.go are now built before the rest of the .go files
so that they are processed by a fast macro expander. This saves time
when using parallel builds.
** put-u8: Always write a single byte, regardless of the port encoding.
** put-u8 now always writes a single byte, regardless of the port encoding.
Previously, (put-u8 PORT OCTET) worked as expected only when writing to
binary ports, i.e. those with port encoding "ISO-8851-1". Strictly
speaking, this meets the requirements of the R6RS 'put-u8', which need
only support binary ports. However, Guile in fact allows binary I/O to
be performed on any port, and yet 'put-u8' behaved in a surprising way
with other port encodings: it would perform a _textual_ I/O operation,
writing the character with Unicode scalar value OCTET. Now, 'put-u8'
always writes a single byte with value OCTET, regardless of the port
encoding.
** Optimize fixnum exact integer square roots.
'exact-integer-sqrt' now avoids heap allocation when applied to a
fixnum. 'sqrt' also avoids heap allocation when applied to a fixnum
that's a perfect square. Fewer heap allocations are now required when
applying 'sqrt' to squares of exact rationals whose numerator or
denominator are fixnums.
** scm_mkstrport: Optimize the POS -> BYTE_POS conversion.
** stexi->shtml: Add support for @i, @math, @tie and @dots.
** SRFI-19: Support ~N in string->date.