8 files changed, 109 insertions, 59 deletions

@@ -1,4 +1,12 @@
-LUA ?= rlwrap luajit
+LUA ?= rlwrap luajit \
+        -e 'pp = require "pp"' \
+        -e 'eval = require "eval"' \
+        -e 'read = require "read"' \
+        -e 'type = require "type"' \
+        -e 'utf8 = require "utf8"' \
+        -e 'util = require "util"' \
+        -e 'test = require "test"'
+
 
 .PHONY: repl
 repl:
@@ -6,14 +14,7 @@ repl:
 
 .PHONY: test
 test:
-        $(LUA) -i \
-                -e 'pp = require "pp"' \
-                -e 'eval = require "eval"' \
-                -e 'read = require "read"' \
-                -e 'type = require "type"' \
-                -e 'utf8 = require "utf8"' \
-                -e 'util = require "util"' \
-                -e 'test = require "test"'
+        $(LUA) -e 'test.runtests()'
 
 .PHONY: check
 check:
@@ -36,6 +36,12 @@ see COPYING for details.
 
 [email me]: mailto:acdw@acdw.net
 
+## references
+
+- [Lua 5.1 reference](https://www.lua.org/manual/5.1/manual.html)
+- [Luajit](https://luajit.org/)
+- [R7RS](https://standards.scheme.org/corrected-r7rs/r7rs.html)
+
 ## thanks
 
 thanks to peter norvig's [series on lisp interpreters][norvig]
@@ -0,0 +1,37 @@
+--- lam.base --- base environment
+
+local base = {}
+local type = require "type"
+local isNull = type.isNull
+
+base.env = {
+        begin =
+                function (r)
+                        local r = r
+                        while not isNull(r.cdr) do
+                                r = r.cdr
+                        end
+                        return r.car
+                end,
+        ["+"] =
+                function (r)
+                        local r, a = r, 0
+                        while r.cdr do
+                                r, a = r.cdr, a + r.car
+                        end
+                        return a
+                end,
+        ["-"] =
+                function (r)
+                        if isNull(r) then return -1 end
+                        if isNull(r.cdr) then return (- r.car) end
+                        local r, a = r.cdr, r.car
+                        while r.cdr do
+                                r, a = r.cdr, a - r.car
+                        end
+                        return a
+                end,
+}
+
+---
+return base
@@ -1,6 +1,7 @@
 --- lam.eval
 
 local eval = {}
+local base = require "base"
 local type = require "type"
 local isNull, isList, isa, List, Cons =
         type.isNull, type.isList, type.isa, type.List, type.Cons
@@ -30,6 +31,7 @@ function eval.Proc (params, body, env)
                                         inner[p.car] = a.car
                                         p, a = p.cdr, a.cdr
                                 end
+                                pp.pp(self.body)
                                 return eval.eval(
                                         self.body,
                                         eval.Env(inner, self.env))
@@ -38,37 +40,8 @@ function eval.Proc (params, body, env)
         return setmetatable(v, mt)
 end
 
-local global = {
-        begin =
-                function (r)
-                        local r = r
-                        while not isNull(r.cdr) do
-                                r = r.cdr
-                        end
-                        return r.car
-                end,
-        ["+"] =
-                function (r)
-                        local r, a = r, 0
-                        while r.cdr do
-                                r, a = r.cdr, a + r.car
-                        end
-                        return a
-                end,
-        ["-"] =
-                function (r)
-                        if isNull(r) then return -1 end
-                        if isNull(r.cdr) then return (- r.car) end
-                        local r, a = r.cdr, r.car
-                        while r.cdr do
-                                r, a = r.cdr, a - r.car
-                        end
-                        return a
-                end,
-}
-
 function eval.eval (x, env)
-        env = env or global
+        env = env or base.env
         if isa(x, "Symbol") then
                 return env[x]
         elseif not isList(x) then
@@ -77,13 +50,13 @@ function eval.eval (x, env)
                 local op, args = x.car, x.cdr
                 if op == "quote" then
                         return args.car
-                elseif op == "define" then
+                elseif op == "define" or op == "def" then
                         env[args.car] = eval.eval(args.cdr.car, env)
                         return nil
-                elseif op == "lambda" then
+                elseif op == "lambda" or op == "lam" then
                         return eval.Proc(
                                 args.car,
-                                Cons("begin", args.cdr),
+                                Cons("begin", args.cdr), -- i don't like this
                                 env)
                 elseif op == "if" then
                         assert(not isNull(args.cdr), "Malformed 'if'")
@@ -7,7 +7,7 @@ local util = require "util"
 local pop = util.pop
 local unpack = table.unpack or unpack
 
-function program_characters (program)
+local function program_characters (program)
         local chars = {}
         for pos, code in utf8.codes(program) do
                 table.insert(chars, code)
@@ -0,0 +1,21 @@
+--- lam.repl
+
+local repl = {}
+local eval = require("eval").eval
+local read = require("read").read
+
+function repl.repl (prompt)
+        if not prompt then prompt = "lam> " end
+        io.input():setvbuf("line")
+        repeat
+                io.write(prompt)
+                io.output():flush()
+                local input = io.read()
+                if input == nil then break end
+                local value = eval(read(input))
+                if value then print(value) end
+        until false
+end
+
+---
+return repl
@@ -1,28 +1,39 @@
 --- lam.test
--- testing helpers
 
 local test = {}
 local eval = require("eval").eval
 local read = require("read").read
+local luatype = require("type").luatype
 
-function test.lambda ()
-        local ls = {
-                [ [[((lambda (x) (+ x x)) 3)]] ] = 6,
-                [ [[((lambda () 100))]] ] = 100,
-                [ [[((lambda (x) 1 2 3) 4)]] ] = 3,
-                [ [[((lambda () 1 2 3))]] ] = 3,
-                [ [[((lambda (x) x (+ x x) (+ x x x)) 9)]] ] = 27,
-        }
-        for l, target in pairs(ls) do
-                io.write(string.format("%s == %s\n\t", l, target))
-                local value = eval(read(l))
-                if value == target then
-                        print "ok"
-                else
-                        print(string.format("not ok : %s", value))
+function test.test (form, expected)
+        local diag = string.format("%s == %s", form, expected)
+        local value = eval(read(form))
+        if value == expected then
+                print(string.format("ok: %s", diag))
+        else
+                print(string.format("not ok: %s != %s", diag, value))
+        end
+end
+
+function test.runtests ()
+        for name, fn in pairs(test) do
+                if luatype(fn) == "function"
+                        and name ~= "test"
+                        and name ~= "runtests"
+                then
+                        print(">>>", name)
+                        fn()
                 end
         end
 end
 
+function test.lambda ()
+        test.test([[((lambda (x) (+ x x)) 3)]], 6)
+        test.test([[((lambda () 100))]], 100)
+        test.test([[((lambda (x) 1 2 3) 4)]], 3)
+        test.test([[((lambda () 1 2 3))]], 3)
+        test.test([[((lambda (x) x (+ x x) (+ x x x)) 9)]], 27)
+end
+
 ---
 return test
@@ -31,6 +31,7 @@ end
 -- Symbols and Numbers are strings and numbers, respectively.  At some point
 -- I'll want to implement a full numeric tower and symbol tables or namespaces
 -- or whatever, but today is not that day
+
 t.Symbol = tostring
 t.Number = tonumber