Python, with no statements!
Inside expr.py you'll find some utility functions and classes that let you write programs without any statements (barring a single import at the top of the file...).
I've written a (sort-of working) TCP server and an HTTP server.
Here's an example of the code you might write. This starts a mutli-threaded TCP server that simply echos whatever you send it. Try it out using netcat. (warning: it's a little broken)
from expr import *
# `do` lets use sequence "statements"
do([
# "walrus operator" gives us variables (python 3.8+)
socket := require('socket'),
threading := require('threading'),
spawn := lambda target, args: do([
handler_thread := threading.Thread(target=target, args=args),
setattr(handler_thread, 'daemon', True),
handler_thread.start()
]),
ends_with_newline := lambda bytes_: \
len(bytes_) > 0 and bytes_[len(bytes_) - 1] == ord('\n'),
handle_client := lambda current_connection, client_addr: do([
print(f"client connected at {client_addr}"),
# loop_while calls the provided lambda over and over, until the final expression is falsy
loop_while(lambda: do([
recvd_bytes := current_connection.recv(1024),
current_connection.send(recvd_bytes),
not ends_with_newline(recvd_bytes),
])),
]),
listen := lambda host, port: do([
connection := socket.socket(socket.AF_INET, socket.SOCK_STREAM),
connection.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1),
connection.bind((host, port)),
# Listen for clients (max 10 clients in waiting)
connection.listen(10),
print(f"server listening on {host}:{port}"),
loop(lambda: do([
client_connection := connection.accept(),
spawn(target=handle_client, args=client_connection),
]))
]),
listen("localhost", 3000)
])The code in http.py and http_server.py is much more interesting. Cool things not included in this snippet:
tis a way to get "data classes". You give it a name and a list of properties, as follows:Pair := t('Pair', ['one', 'two'])Boxis to get around the fact that we don't have mutable bindings. Instead of the binding being mutable, just stick it in a container!klass, for when a data class isn't enough. Used to defineBox:
Box = klass('Box', {
'__init__': lambda self, value: setattr(self, 'value', value),
'get': lambda self: self.value,
'set': lambda self, setter: setattr(self, 'value', setter(self.value)),
})- Exceptions! There's no way to catch exceptions at the moment. It would be easy to write a helper function using
try/catchstatements, but that's cheating.
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