Improve Python and Linenoise

This change reinvents all the GNU Readline features I discovered that I
couldn't live without, e.g. UTF-8, CTRL-R search and CTRL-Y yanking. It
now feels just as good in terms of user interface from the subconscious
workflow perspective. It's real nice to finally have an embeddable line
reader that's actually good with a 30 kb footprint and a bsd-2 license.

This change adds a directory to the examples folder, explaining how the
new Python compiler may be used.  Some of the bugs with Python binaries
have been addressed but overall it's still a work in progress.

examples/pyapp/pyapp.mk

@@ -0,0 +1,116 @@
+#-*-mode:makefile-gmake;indent-tabs-mode:t;tab-width:8;coding:utf-8-*-┐
+#───vi: set et ft=make ts=8 tw=8 fenc=utf-8 :vi───────────────────────┘
+#
+# SYNOPSIS
+#
+#   Actually Portable Python Tutorial
+#
+# DESCRIPTION
+#
+#   This tutorial demonstrates how to compile Python apps as tiny
+#   static multiplatform APE executables as small as 1.9m in size
+#   using Cosmopolitan, which is a BSD-style multitenant codebase
+#
+# GETTING STARTED
+#
+#   # run these commands after cloning the cosmo repo on linux
+#   $ make -j8 o//examples/pyapp/pyapp.com
+#   $ o//examples/pyapp/pyapp.com
+#   cosmopolitan is cool!
+#
+# HOW IT WORKS
+#
+#   $ pyobj.com -m -o pyapp.o pyapp.py
+#   $ ld -static -nostdlib -T o//ape/ape.lds ape.o crt.o \
+#       pyapp.o \
+#       cosmopolitan-python-stage2.a \
+#       cosmopolitan-sqlite3.a \
+#       cosmopolitan-linenoise.a \
+#       cosmopolitan-bzip2.a \
+#       cosmopolitan-python-stage1.a \
+#       cosmopolitan.a
+#   $ ./pyapp.com
+#   cosmopolitan is cool!
+#
+# NOTES
+#
+#   If you enjoy this tutorial, let us know jtunney@gmail.com. If
+#   you're building something cool, then we can we can add you to
+#   our .gitowners file which grants you commit access so you can
+#   indepnedently maintain your package, as part of the mono-repo
+
+PKGS      += PYAPP
+PYAPP      = $(PYAPP_DEPS) o/$(MODE)/examples/pyapp/pyapp.a
+PYAPP_COMS = o/$(MODE)/examples/pyapp/pyapp.com
+PYAPP_BINS = $(PYAPP_COMS) $(PYAPP_COMS:%=%.dbg)
+
+# Specify our Cosmopolitan library dependencies
+#
+# - THIRD_PARTY_PYTHON_STAGE1 plus THIRD_PARTY_PYTHON_STAGE2 will
+#   define the Python CAPI and supported standard library modules
+#
+PYAPP_DIRECTDEPS = \
+	THIRD_PARTY_PYTHON_STAGE2
+
+# Compute the transitive closure of dependencies. There's dozens of
+# other static libraries we need, in order to build a static binary
+# such as fmt.a, runtime.a, str.a etc. This magic statement figures
+# them all out and arranges them in the correct order.
+PYAPP_DEPS := $(call uniq,$(foreach x,$(PYAPP_DIRECTDEPS),$($(x))))
+
+# # Asks PYOBJ.COM to turn our Python source into an ELF object which
+# # contains (a) embedded zip file artifacts of our .py file and .pyc
+# # which it it compiled; and (b) statically analyzed listings of our
+# # python namespaces and imports that GNU ld will use for tree shake
+# # NOTE: This code can be commented out since it's in build/rules.mk
+# o/$(MODE)/examples/pyapp/pyapp.o: examples/pyapp/pyapp.py o/$(MODE)/third_party/python/pyobj
+# 	o/$(MODE)/third_party/python/pyobj $(PYFLAGS) -o $@ $<
+
+# We need to define how the repository source code path gets mapped
+# into an APE ZIP file path. By convention, we place Python modules
+# in `.python/` (which is accessible via open() system calls, using
+# the synthetic path `"/zip/.python/"`) which means that if we want
+# to turn `pyapp/pyapp.py` into `.python/pyapp.py` so it's imported
+# using `import pyapp` then we can simply append to PYOBJ.COM flags
+# flags above asking it to strip one directory component and prefix
+# Lastly be sure that whenever you use this variable override trick
+# you only do it to .o files, since otherwise it'll ruin everything
+# Passing -m to PYOBJ.COM causes a C main() function to get yoinked
+# and it means our Python module can no longer be used as a library
+o/$(MODE)/examples/pyapp/pyapp.o: PYFLAGS += -m -C2 -P.python
+
+# Asks PACKAGE.COM to sanity check our DIRECTDEPS and symbol graph.
+# This program functions as an incremental linker. It also provides
+# enhancements to the object code that GCC generated similar to LTO
+# so be certain that your .com.dbg rule depends on the .pkg output!
+o/$(MODE)/examples/pyapp/pyapp.pkg: \
+		o/$(MODE)/examples/pyapp/pyapp.o \
+		$(foreach x,$(PYAPP_DIRECTDEPS),$($(x)_A).pkg)
+
+# Ask GNU LD to link our APE executable within an ELF binary shell.
+# The CRT and APE dependencies are special dependencies that define
+# your _start() / WinMain() entrpoints as well as APE linker script
+o/$(MODE)/examples/pyapp/pyapp.com.dbg: \
+		$(PYAPP_DEPS) \
+		o/$(MODE)/examples/pyapp/pyapp.pkg \
+		o/$(MODE)/examples/pyapp/pyapp.o \
+		$(CRT) \
+		$(APE)
+	$(LINK) $(LINKARGS) -o $@
+
+# # Unwrap the APE .COM binary, that's embedded within the linked file
+# # NOTE: This line can be commented out, since it's in build/rules.mk
+# o/$(MODE)/examples/pyapp/pyapp.com: \
+# 		o/$(MODE)/examples/pyapp/pyapp.com.dbg
+# 	$(OBJCOPY) -S -O binary $< $@
+
+# Ensure that build config changes will invalidate build artifacts.
+o/$(MODE)/examples/pyapp/pyapp.o: \
+		examples/pyapp/pyapp.mk
+
+# By convention we want to be able to say `make -j8 o//examples/pyapp`
+# and have it build all targets the package defines.
+.PHONY: o/$(MODE)/examples/pyapp
+o/$(MODE)/examples/pyapp: \
+		o/$(MODE)/examples/pyapp/pyapp.com \
+		o/$(MODE)/examples/pyapp/pyapp.com.dbg

examples/pyapp/pyapp.py

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+def main():
+  print('cosmopolitan is cool!')
+if __name__ == '__main__':
+  main()