I've been struggling to make the repl experience not suck in wart -- without getting into the complexities of non-blocking I/O -- and just thought up a twist on the usual prompt. I'd appreciate anybody with access to linux or a mac trying it out:
Play with it for a minute and give me brief impressions? You can also call me at 512 422 0223 (US) if that's more convenient. Did it make sense or was it bewildering? Should I retreat to a more conventional prompt?
PS: Don't read the comments first, lest they give away the punchline :)
[kdd@780 wart]$ ./wart
g++ -O3 -std=gnu++0x -Wall -Wextra -fno-strict-aliasing boot.cc -o wart_bin
In file included from file_list:21:0,
from boot.cc:75:
029posix.cc: In function ‘Cell* compiledFn_socket()’:
029posix.cc:47:1: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
which: no rlwrap in (/usr/local/bin: ... )
ready! type in an expression, then hit enter twice. ctrl-d exits.
(+ 22 22)
=> 44
(prn "hello")
hello
=> "hello"
Ran it on Arch Linux (3.6) and played around. Looks pretty good though I'm not so sure about the double enter requirement. Very superficially I'd say I prefer the empty line after the result, keeping the expression and result together and segregating each expression/result set; the absence of a prompt looks quite good:
"Looks pretty good though I'm not so sure about the double enter requirement."
It's not just wart: readable has the same issue. The problem is that you don't know if the user is finished or if they want to enter a multi-line expression. With parentheses, you always know whether the expression is completed or not, but with whitespace, you don't.
The same is true even in Python. If you type in this:
>>> def foo(x):
... return x
You have to hit enter twice. In some cases, Python is smart enough to know that the expression ended, so you only have to hit enter once:
>>> 1 + 2
But that's because Python's grammar is more restricted in certain areas. That doesn't work with S-expressions because they're so general.
I realized after I'd read wart's readme that parens were optional, though I don't think that would have been enough to clue me in on the double enter requirement. :)
Yeah, I didn't expect everyone to remember that :) I just wanted a sense of whether the no-prompt prompt was intuitive. So far it seems to be intuitive!
Thanks a lot for the comments! Pauan's right that the indent sensitivity seems to require the two newlines, and it is indeed weird that responses get grouped with the next command. I'm still looking for a better approach.
I'm interested in that warning you get. Are you on a 64-bit system? Could you type in the following into gdb and share the results?
$ gdb -q
(gdb) p sizeof(int)
(gdb) p sizeof(long)
(gdb) p sizeof(void*)
Edit: I just noticed that gdb on my machine gives different results with and without a binary. So you'll need to invoke it from the wart directory like so:
Also, it seems that error message came up only the first time I ran wart. I haven't seen it in later executions so there's probably no need for any additional concern. :)
It comes up when building the C files. Since you haven't made any changes to the sources since there's no need to rebuild. But you can see it again if you first run:
Thanks a lot! Yes, wart doesn't support bignums yet. Its arithmetic is that of the underlying C, which on a 64-bit machine can handle factorial of 20, but not 21.
