Add -> functions to core

2 files changed, 83 insertions, 2 deletions

@@ -2,8 +2,11 @@
 
 local dump = require("dump")
 local type = require("type")
+local utf8 = require("utf8")
 local null = type.null
-local assert_arity = type.assert_arity
+local assert_arity, assert_type = type.assert_arity, type.assert_type
+local util = require("util")
+local error = util.error
 
 local function fold (kons, knil, r)
         if r == null then
@@ -53,6 +56,80 @@ for _, t in ipairs {
         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(utf8.char(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)
@@ -10,7 +10,11 @@ m.luaerror = error
 -- WHERE is where in the process; DESC is a description of the error; the rest
 -- are "irritants"
 function m.error (desc, ...)
-        m.luaerror(string.format("%s: %s", desc, table.concat({...}, " ")
+        local irritants = {}
+        for _, i in ipairs({...}) do
+                table.insert(irritants, tostring(i))
+        end
+        m.luaerror(string.format("%s: %s", desc, table.concat(irritants, ", ")
         ))
 end