1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
--- lam.repl
local m = {}
local _r = require("read")
local read, inport, read_string, eof =
_r.read, _r.inport, _r.read_string, _r.eof
local eval = require("eval").eval
local function schemeprint (x)
-- if x == nil then return end
if x == true then
print("#t")
elseif x == false then
print("#f")
elseif x == nil then
print("#<nil>")
else
print(x)
end
end
local lam = [[
@,,,@
<|^ ^|> l a m
| /) 0015
|I /))) acdw
-------------
]]
local function handle_error (e)
local start = e:find(": ")
return e:sub(start + 2)
end
function m.read_eval (filename, interactive)
-- interactive = { out = file or handle, prompt = string, }
local inport = inport(filename)
local prompt = interactive and interactive.prompt or "> "
if interactive then
io.output(interactive.out or io.stdout)
io.write(lam)
io.output():setvbuf("line")
else
io.output(io.stdout) -- hmmm
io.output():setvbuf("no")
end
repeat
if interactive then
io.stderr:write(prompt)
io.stderr:flush()
end
-- read
local ok, x = xpcall(
function ()
local nxt = read(inport)
return nxt
end,
handle_error
)
if not ok then
io.stderr:write("(read) not ok: ", x, "\n")
-- in interactive mode, errors should not be fatal. in
-- batch mode, they should be.
if not interactive then return nil end
end
-- eval
if ok then
local ok, v = xpcall(
function () return eval(x) end,
handle_error
)
if not ok then
io.stderr:write("(eval) not ok: ", v, "\n")
if not interactive then return nil end
end
-- print
if ok and interactive then schemeprint(v) end
elseif interactive then
ok = "recover"
end
until x == eof -- loop
inport:close()
end
function m.repl (prompt)
return m.read_eval(nil, { prompt = prompt, })
end
function m.load (filename)
return m.read_eval(filename)
end
--------
return m
|
