Thun/implementations/Elm/src/Joy.elm

456 lines
14 KiB
Elm

module Joy exposing (doit, JoyDict)
import Bitwise
import Dict exposing (Dict)
import Result exposing (andThen)
import String exposing (replace, words)
type JoyType
= JoySymbol String
| JoyInt Int
| JoyList (List JoyType)
| JoyTrue
| JoyFalse
type alias JList = List JoyType
type alias JoyDict = Dict String JList
joy : JList -> JList -> JoyDict -> Result String (JList, JoyDict)
joy stack expression dict =
case expression of
[] ->
Ok (stack, dict)
term :: rest_of_expression ->
case term of
JoySymbol symbol ->
case joy_eval symbol stack rest_of_expression dict of
Err msg -> Err msg
Ok (s, e, dict0) -> joy s e dict0
_ ->
joy (term :: stack) rest_of_expression dict
joy_eval : String -> JList -> JList -> JoyDict -> Result String (JList, JList, JoyDict)
joy_eval symbol stack expression dict =
if symbol == "" then
Ok (stack, expression, dict)
else
case joy_function_eval symbol stack expression of
Err msg ->
if "Unknown word." == msg then
-- Look up word in dictionary.
Err ("Unknown word: " ++ symbol)
else
Err msg
Ok (stack0, expression0) -> Ok (stack0, expression0, dict)
joy_function_eval symbol stack expression =
case symbol of
"branch" -> joy_branch stack expression
"i" -> joy_i stack expression
"dip" -> joy_dip stack expression
"loop" -> joy_loop stack expression
"+" -> joy_binary_math_op (+) stack expression
"-" -> joy_binary_math_op (-) stack expression
"*" -> joy_binary_math_op (*) stack expression
"/" -> joy_binary_math_op (//) stack expression
"%" -> joy_binary_math_op (modBy) stack expression
"<" -> joy_comparison_op (<) stack expression
">" -> joy_comparison_op (>) stack expression
"<=" -> joy_comparison_op (<=) stack expression
">=" -> joy_comparison_op (>=) stack expression
"<>" -> joy_comparison_op (/=) stack expression
"!=" -> joy_comparison_op (/=) stack expression
"=" -> joy_comparison_op (==) stack expression
"and" -> joy_binary_math_op (Bitwise.and) stack expression
"or" -> joy_binary_math_op (Bitwise.or) stack expression
"xor" -> joy_binary_math_op (Bitwise.xor) stack expression
"lshift" -> joy_binary_math_op (swap_args Bitwise.shiftLeftBy) stack expression
"<<" -> joy_binary_math_op (swap_args Bitwise.shiftLeftBy) stack expression
"rshift" -> joy_binary_math_op (swap_args Bitwise.shiftRightBy) stack expression
">>" -> joy_binary_math_op (swap_args Bitwise.shiftRightBy) stack expression
"/\\" -> joy_logical_op (&&) stack expression
"\\/" -> joy_logical_op (||) stack expression
"_\\/_" -> joy_logical_op (xor) stack expression
"clear" -> Ok ([], expression)
"concat" -> joy_concat stack expression
"cons" -> joy_cons stack expression
"dup" -> joy_dup stack expression
"first" -> joy_first stack expression
"pop" -> joy_pop stack expression
"rest" -> joy_rest stack expression
"stack" -> joy_stack stack expression
"swaack" -> joy_swaack stack expression
"swap" -> joy_swap stack expression
"truthy" -> joy_truthy stack expression
_ -> Err ("Unknown word.")
-- _ -> Err ("Unknown word: " ++ symbol)
joy_branch : JList -> JList -> Result String (JList, JList)
joy_branch stack expression =
case pop_list(stack) of
Ok (true_body, s0) ->
case pop_list(s0) of
Ok (false_body, s1) ->
case pop_bool(s1) of
Ok (flag, s2) ->
if flag then
Ok (s2, true_body ++ expression)
else
Ok (s2, false_body ++ expression)
Err msg -> Err msg
Err msg -> Err msg
Err msg -> Err msg
joy_i : JList -> JList -> Result String (JList, JList)
joy_i stack expression =
case pop_list(stack) of
Ok (a, s0) -> Ok (s0, a ++ expression)
Err msg -> Err msg
joy_dip : JList -> JList -> Result String (JList, JList)
joy_dip stack expression =
case pop_list(stack) of
Ok (quoted_expression, s0) ->
case pop_any(s0) of
Ok (x, s1) -> Ok (s1, quoted_expression ++ (x :: expression))
Err msg -> Err msg
Err msg -> Err msg
joy_loop : JList -> JList -> Result String (JList, JList)
joy_loop stack expression =
case pop_list(stack) of
Ok (loop_body, s0) ->
case pop_bool(s0) of
Ok (flag, s1) ->
if flag then
Ok (s1, loop_body ++ ((JoyList loop_body) :: (JoySymbol "loop") :: expression))
else
Ok (s1, expression)
Err msg -> Err msg
Err msg -> Err msg
joy_binary_math_op : (Int -> Int -> Int) -> JList -> JList -> Result String (JList, JList)
joy_binary_math_op op stack expression =
case pop_int(stack) of
Ok (a, s0) ->
case pop_int(s0) of
Ok (b, s1) ->
Ok ((push_int (op b a) s1), expression)
Err msg -> Err msg
Err msg -> Err msg
swap_args : (Int -> Int -> Int) -> (Int -> Int -> Int)
swap_args op = (\a b -> op b a)
joy_comparison_op : (Int -> Int -> Bool) -> JList -> JList -> Result String (JList, JList)
joy_comparison_op op stack expression =
case pop_int(stack) of
Ok (a, s0) ->
case pop_int(s0) of
Ok (b, s1) ->
Ok ((push_bool (op b a) s1), expression)
Err msg -> Err msg
Err msg -> Err msg
joy_logical_op : (Bool -> Bool -> Bool) -> JList -> JList -> Result String (JList, JList)
joy_logical_op op stack expression =
case pop_bool(stack) of
Ok (a, s0) ->
case pop_bool(s0) of
Ok (b, s1) ->
Ok ((push_bool (op b a) s1), expression)
Err msg -> Err msg
Err msg -> Err msg
joy_concat : JList -> JList -> Result String (JList, JList)
joy_concat stack expression =
case pop_list(stack) of
Ok (a, s0) ->
case pop_list(s0) of
Ok (b, s1) ->
Ok ((push_list (b ++ a) s1), expression)
Err msg -> Err msg
Err msg -> Err msg
joy_cons : JList -> JList -> Result String (JList, JList)
joy_cons stack expression =
case pop_list(stack) of
Ok (a, s0) ->
case pop_any(s0) of
Ok (b, s1) ->
Ok ((push_list (b :: a) s1), expression)
Err msg -> Err msg
Err msg -> Err msg
joy_dup : JList -> JList -> Result String (JList, JList)
joy_dup stack expression =
case pop_any(stack) of
Ok (a, s0) -> Ok ((a :: stack), expression)
Err msg -> Err msg
joy_first : JList -> JList -> Result String (JList, JList)
joy_first stack expression =
case pop_list(stack) of
Ok (a, s0) ->
case pop_any(a) of
Ok (b, _) -> Ok ((push_any b s0), expression)
Err _ -> Err "Cannot take first of empty list."
Err msg -> Err msg
joy_pop : JList -> JList -> Result String (JList, JList)
joy_pop stack expression =
case pop_any(stack) of
Ok (_, s0) -> Ok (s0, expression)
Err msg -> Err msg
joy_rest : JList -> JList -> Result String (JList, JList)
joy_rest stack expression =
case pop_list(stack) of
Ok (a, s0) ->
case pop_any(a) of
Ok (_, el) -> Ok ((push_list el s0), expression)
Err _ -> Err "Cannot take rest of empty list."
Err msg -> Err msg
joy_stack : JList -> JList -> Result String (JList, JList)
joy_stack stack expression =
Ok ((push_list stack stack), expression)
joy_swaack : JList -> JList -> Result String (JList, JList)
joy_swaack stack expression =
case pop_list(stack) of
Ok (s, s0) -> Ok ((push_list s0 s), expression)
Err msg -> Err msg
joy_swap : JList -> JList -> Result String (JList, JList)
joy_swap stack expression =
case pop_any(stack) of
Ok (a, s0) ->
case pop_any(s0) of
Ok (b, s1) -> Ok ((b :: a :: s1), expression)
Err msg -> Err msg
Err msg -> Err msg
joy_truthy : JList -> JList -> Result String (JList, JList)
joy_truthy stack expression =
case pop_any(stack) of
Ok (a, s0) ->
case a of
JoyTrue -> Ok (stack, expression)
JoyFalse -> Ok (stack, expression)
JoyInt i ->
if 0 == i then
Ok (JoyFalse :: s0, expression)
else
Ok (JoyTrue :: s0, expression)
JoyList el ->
if [] == el then
Ok (JoyFalse :: s0, expression)
else
Ok (JoyTrue :: s0, expression)
JoySymbol _ ->
Err "Cannot Boolify."
Err msg -> Err msg
push_bool : Bool -> JList -> JList
push_bool flag stack =
if flag then
JoyTrue :: stack
else
JoyFalse :: stack
push_int : Int -> JList -> JList
push_int i stack = (JoyInt i) :: stack
push_list : JList -> JList -> JList
push_list el stack = (JoyList el) :: stack
push_any : JoyType -> JList -> JList
push_any j stack = j :: stack
pop_int : JList -> Result String (Int, JList)
pop_int stack = pop_any stack |> andThen isnt_int
pop_list : JList -> Result String (JList, JList)
pop_list stack = pop_any stack |> andThen isnt_list
pop_bool : JList -> Result String (Bool, JList)
pop_bool stack = pop_any stack |> andThen isnt_bool
pop_any : JList -> Result String (JoyType, JList)
pop_any stack =
case stack of
[] ->
Err "Not enough values on Stack"
item :: rest ->
Ok (item, rest)
isnt_int : (JoyType, JList) -> Result String (Int, JList)
isnt_int (item, stack) =
case item of
JoyInt i ->
Ok (i, stack)
_ ->
Err "Not an integer."
isnt_list : (JoyType, JList) -> Result String (JList, JList)
isnt_list (item, stack) =
case item of
JoyList el ->
Ok (el, stack)
_ ->
Err "Not a list."
isnt_bool : (JoyType, JList) -> Result String (Bool, JList)
isnt_bool (item, stack) =
case item of
JoyTrue -> Ok (True, stack)
JoyFalse -> Ok (False, stack)
_ -> Err "Not a Boolean value."
-- Printer
joyTermToString : JoyType -> String
joyTermToString term =
case term of
JoySymbol name -> name
JoyInt n -> String.fromInt n
JoyTrue -> "true"
JoyFalse -> "false"
JoyList list ->
"[" ++ (joyExpressionToString list) ++ "]"
joyExpressionToString expr = String.join " " (List.map joyTermToString expr)
-- Use the old S-expression lexing trick.
tokenize : String -> (List String)
tokenize text = words (replace "[" " [ " (replace "]" " ] " text))
tokenator : String -> JoyType
tokenator tok =
case tok of
"true" -> JoyTrue
"false" -> JoyFalse
_ -> case String.toInt tok of
Just i -> JoyInt i
Nothing -> JoySymbol tok
-- I don't like this because it won't reject "[" and "]"
-- instead turning them into symbols!
expect_right_bracket : (List String) -> JList -> Result String (JList, List String)
expect_right_bracket tokens acc =
case tokens of
[] -> Err "Missing closing bracket."
h :: t -> expect_right_bracket_one_token_lookahead h t acc
expect_right_bracket_one_token_lookahead : String -> (List String) -> JList -> Result String (JList, List String)
expect_right_bracket_one_token_lookahead token tokens acc =
case token of
"]" -> Ok (acc, tokens)
"[" ->
-- (* extract the sub-list *)
case expect_right_bracket tokens [] of
Err msg -> Err msg
Ok (sub_list, rest) ->
-- (* continue looking for the expected "]" *)
case expect_right_bracket rest acc of
Err msg -> Err msg
Ok (el, rrest) ->
Ok ((JoyList sub_list) :: el, rrest)
_ ->
case expect_right_bracket tokens acc of
Err msg -> Err msg
Ok (el, rest) ->
Ok ((tokenator token) :: el, rest)
---(* token -> token list -> joy_type * token list *)
one_token_lookahead : String -> (List String) -> Result String (JoyType, List String)
one_token_lookahead token tokens =
case token of
"]" -> Err "Extra closing bracket."
"[" -> case expect_right_bracket tokens [] of
Err msg -> Err msg
Ok (list_term, rest_of_tokens) -> Ok (JoyList list_term, rest_of_tokens)
_ -> Ok (tokenator token, tokens)
parse0 : (List String) -> JList -> Result String JList
parse0 tokens acc =
case tokens of
[] -> Ok acc
token :: tokens_tail ->
case one_token_lookahead token tokens_tail of
Err msg -> Err msg
Ok (term, rest_of_tokens) ->
case parse0 rest_of_tokens acc of
Err msg -> Err msg
Ok terms -> Ok (term :: terms)
parse tokens = parse0 tokens []
text_to_expression text = parse (tokenize text)
doit : String -> JoyDict -> Result String (String, JoyDict)
doit text dict =
case text_to_expression text of
Ok ast ->
case joy [] ast dict of
Ok (expr, dict0) -> Ok (joyExpressionToString expr, dict0)
Err msg -> Err msg
Err msg -> Err msg