2 files changed, 84 insertions, 67 deletions

@@ -7,10 +7,31 @@ local pop = require("util").pop
 
 -- TODO:
 -- - string reading
--- - # syntax
--- - comments
 -- - probably more
 
+m.eof = setmetatable({}, {
+                __type = "EOF",
+                __tostring = function () return "#<eof>" end,
+})
+
+local function inport_next_token (port)
+        local tok, toktype
+        while true do
+                if #port.line == 0 then
+                        if port.file then
+                                local ln = port.file:read()
+                                if ln == nil then return m.eof end
+                                port.line = m.tochars(ln)
+                        else
+                                return nil
+                        end
+                end
+                tok, toktype, port.line = m.scan(port.line)()
+                port.line = port.line or {}
+                if tok ~= nil then return tok, toktype end
+        end
+end
+
 function m.inport (source, kind)
         -- KIND can be one of "file", "string"; defaults to "file"
         -- SOURCE is the name of the file or the string to read, or nil; if nil,
@@ -18,9 +39,9 @@ function m.inport (source, kind)
         local f, l
         local k = kind or "file"
         if source then
-                if kind == "file" then
+                if k == "file" then
                         f = io.open(source, "r")
-                elseif kind == "string" then
+                elseif k == "string" then
                         l = m.tochars(source)
                 end
         else
@@ -29,25 +50,10 @@ function m.inport (source, kind)
         end
         local t = {
                 file = f,
+                filename = source,
+                kind = kind,
                 line = l or {},
-                next_token =
-                        function (self)
-                                local tok, toktype
-                                while true do
-                                        if #self.line == 0 and self.file then
-                                                self.line = m.tochars(
-                                                        self.file:read("*l"))
-                                        end
-                                        if not self.line or #self.line == 0 then
-                                                return nil
-                                        end
-                                        tok, toktype, self.line =
-                                                m.scan(self.line)()
-                                        if tok ~= nil then
-                                                return tok, toktype
-                                        end
-                                end
-                        end,
+                next_token = inport_next_token,
         }
         if t.file then t.close = function (self) self.file:close() end; end
         local mt = {
@@ -232,12 +238,12 @@ m.readmacros = {
                         table.insert(Q, m.read(port))
                         return t.list(Q)
                 end,
-        comment = idf(nil),
+        comment = idf(nil)
 }
 
 function m.read (port)
         local function read_ahead (tok, toktype)
-                if tok == nil then error("Unexpected EOF") end
+                if tok == m.eof then error("Unexpected EOF") end
                 if toktype == "open" then
                         local L = {}
                         while true do
@@ -262,7 +268,7 @@ function m.read (port)
         end
         -- body of read
         local tok1, toktype1 = port:next_token()
-        if tok1 == nil then return nil
+        if tok1 == m.eof then return m.eof
         else return read_ahead(tok1, toktype1)
         end
 end
@@ -1,9 +1,10 @@
 --- lam.repl
 
 local m = {}
-local read = require("read")
-local eval = require("eval")
-local pp = require("dump").pp
+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
@@ -12,7 +13,7 @@ local function schemeprint (x)
         elseif x == false then
                 print("#f")
         elseif x == nil then
-                print("#n")
+                print("#<nil>")
         else
                 print(x)
         end
@@ -26,57 +27,67 @@ local lam = [[
  -------------
 ]]
 
-function m.repl (prompt, infile, out)
-        -- PROMPT should be a string, INFILE is a filename, and OUT is either a
-        -- filename, nil (in which case it will be stdout), or false (which
-        -- suppresses output)
-        local inport = read.inport(infile)
-        if out ~= false then
-                io.output(out)
+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
-        io.output():setvbuf("line")
-        if prompt then
-                stderr = io.open("/dev/stderr", "w") -- Linux-only !
-        end
-        while true do -- loop
-                if prompt then
-                        stderr:write(prompt)
-                        stderr:flush()
+        repeat
+                if interactive then
+                        io.stderr:write(prompt)
+                        io.stderr:flush()
                 end
                 -- read
                 local ok, x = xpcall(
-                        function () return read.read(inport) end,
-                        function (e)
-                                local start = e:find(": ")
-                                return e:sub(start+2)
-                        end
+                        function ()
+                                local nxt = read(inport)
+                                return nxt
+                        end,
+                        handle_error
                 )
                 if not ok then
-                        print("(read) not ok: " .. x)
-                        x = nil
+                        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 x then
-                        local ok, val =
-                                xpcall(
-                                        function () return eval.eval(x) end,
-                                        function (e)
-                                                local start = e:find(": ")
-                                                return e:sub(start+2)
-                                        end
-                                )
+                if ok then
+                        local ok, v = xpcall(
+                                function () return eval(x) end,
+                                handle_error
+                        )
                         if not ok then
-                                print("(eval) not ok: " .. val)
-                        elseif out ~= false then
-                                -- print
-                                schemeprint(val)
+                                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
-        end
+        until x == eof -- loop
         inport:close()
-        stderr:close()
-        io.output():close()
+end
+
+function m.repl (prompt)
+        return m.read_eval(nil, { prompt = prompt, })
+end
+
+function m.load (filename)
+        return m.read_eval(filename)
 end
 
 --------