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--- lam.core --- core procedures
local dump = require("dump")
local type = require("type")
local assert_arity, assert_type = type.assert_arity, type.assert_type
local null = type.null
local error = require("util").error
local function fold (kons, knil, r)
if r == null then
return knil
else
local step, early_return = kons(r[1], knil)
if early_return then return early_return end
return fold(kons, step, r[2])
end
end
local env = type.environment({}, {})
env["interaction-environment"] = function (r)
assert_arity(r,0,0)
return env
end
---[[ EQUIVALENCE ]]---
env["eqv?"] = function (r)
assert_arity(r,2,2)
return r[1] == r[2][1]
end
-- from what i understand of the spec, it's okay that eqv? and eq? are the same
env["eq?"] = env["eqv?"]
---[[ VALUES ]]---
env.values = function (r)
return table.unpack(type.totable(r))
end
---[[ TYPES ]]---
env["boolean?"] = function (r)
assert_arity(r,1,1)
return r[1] == false or r[1] == true
end
env["port?"] = function (r)
assert_arity(r,1,1)
return type.isp(r[1], "input-port") or type.isp(r[1], "output-port")
end
for _, t in ipairs {
"symbol",
-- todo: vector
"procedure",
"pair",
"number",
"string",
"port",
} do
env[t.."?"] = function (r)
assert_arity(r,1,1)
return type.isp(r[1], t)
end
end
---[[ CONVERTING BETWEEN TYPES ]]---
env["symbol->string"] = function (r)
assert_arity(r,1,1)
assert_type(r[1], "symbol")
return type.string(r[1])
end
env["string->symbol"] = function (r)
assert_arity(r,1,1)
assert_type(r[1], "string")
return r[1].v
end
env["number->string"] = function (r) -- (z . radix)
assert_arity(r,1,2)
assert_type(r[1], "number")
-- todo: assert radix type
local z, radix = r[1], r[2][1] or 10
local n = {}
if radix == 10 then return type.string(z) end
repeat
local mod = z % radix
if mod > 9 then
mod = string.sub("abcdefghijklmnopqrstuvwxyz", mod-9, 1)
end
table.insert(n, 1, z % radix)
z = math.floor(z/radix)
until z == 0
return type.string(n)
end
env["string->number"] = function (r) -- (z . radix)
assert_arity(r,1,2)
assert_type(r[1], "string")
-- todo: assert radix type
print(require('dump').dump(r))
return tonumber(r[1].v, r[2][1]) or false
end
env["char->integer"] = function (r)
assert_arity(r,1,1)
assert_type(r[1], "char")
return r[1].u
end
env["integer->char"] = function (r)
assert_arity(r,1,1)
assert_type(r[1], "number") -- todo: check integer
return type.character(r[1])
end
env["string->list"] = function (r)
assert_arity(r,1,1)
assert_type(r[1], "string")
local t = {}
for _, c in ipairs(r[1]) do
table.insert(t, type.character(c))
end
return type.list(t)
end
env["list->string"] = function (r)
assert_arity(r,1,1)
if not type.listp(r[1]) then
error("not a list", r[1])
end
local t = {}
for _, c in ipairs(type.totable(r[1])) do
table.insert(t, c.v)
end
return type.string(t)
end
---[[ NUMBERS ]]---
env["="] = function (r)
if r[1] == nil then return true end
if r[2] == nil then return true end
while r[2] ~= null do
if r[1] ~= r[2][1] then return false end
r = r[2]
end
return true
end
env["<"] = function (r)
if r[1] == nil then return true end
if r[2] == nil then return true end
while r[2] ~= null do
if r[1] >= r[2][1] then return false end
r = r[2]
end
return true
end
env[">"] = function (r)
if r[1] == nil then return true end
if r[2] == nil then return true end
while r[2] ~= null do
if r[1] <= r[2][1] then return false end
r = r[2]
end
return true
end
env["<="] = function (r) return not env[">"](r) end
env[">="] = function (r) return not env["<"](r) end
env["+"] = function (r)
return fold(function (a, b) return a + b end, 0, r)
end
env["-"] = function (r)
if r == null then return -1 end
if r[2] == null then return (- r[1]) end
return fold(function (a, b)
return a - b
end, r[1], r[2])
end
env["*"] = function (r)
local function go (a, b)
if a == 0 or b == 0 then
return 0, 1
end
return a * b
end
return fold(go, 1, r)
end
env["/"] = function (r)
assert_arity(r,1)
if r[2] == null then return (1 / r[1]) end
return fold(function (a, b) return a / b end,
r[1], r[2])
end
---[[ STRINGS ]]---
env["string-append"] = function (r)
assert_arity(r,1)
local ss = type.totable(r)
local new = {}
for i, s in ipairs(ss) do
new[i] = s.v
end
return type.string(table.concat(new))
end
---[[ INPUT / OUTPUT ]]---
env.dump = function (r)
assert_arity(r,1,1)
return dump.dump(r[1])
end
env.display = function (r)
assert_arity(r,1,1)
io.write(tostring(r[1]))
io.flush()
end
env.newline = function (r)
assert_arity(r,0,0)
io.write("\n")
io.flush()
end
--------
return {
environment = env,
}
|
