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033892777a
See issue #587. * Merge eval-ast and eval into a single conditional. * Expand macros during the apply phase, removing lots of duplicate tests, and increasing the overall consistency by allowing the macro to be computed instead of referenced by name (`((defmacro! cond (...)))` is currently illegal for example). * Print "EVAL: $ast" at the top of EVAL if DEBUG-EVAL exists in the MAL environment. * Remove macroexpand and quasiquoteexpand special forms. * Use pattern-matching style in process/step*.txt. Unresolved issues: c.2: unable to reproduce with gcc 11.12.0. elm: the directory is unchanged. groovy: sometimes fail, but not on each rebuild. nasm: fails some new soft tests, but the issue is unreproducible when running the interpreter manually. objpascal: unreproducible with fpc 3.2.2. ocaml: unreproducible with 4.11.1. perl6: unreproducible with rakudo 2021.09. Unrelated changes: Reduce diff betweens steps. Prevent defmacro! from mutating functions: c forth logo miniMAL vb. dart: fix recent errors and warnings ocaml: remove metadata from symbols. Improve the logo implementation. Encapsulate all representation in types.lg and env.lg, unwrap numbers. Replace some manual iterations with logo control structures. Reduce the diff between steps. Use native iteration in env_get and env_map Rewrite the reader with less temporary strings. Reduce the number of temporary lists (for example, reverse iteration with butlast requires O(n^2) allocations). It seems possible to remove a few exceptions: GC settings (Dockerfile), NO_SELF_HOSTING (IMPLS.yml) and step5_EXCLUDES (Makefile.impls) .
93 lines
3.2 KiB
Standard ML
93 lines
3.2 KiB
Standard ML
exception NotDefined of string
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exception NotApplicable of string
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fun read s =
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readStr s
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fun eval e ast = (
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case lookup e "DEBUG-EVAL" of
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SOME(x) => if truthy x
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then TextIO.print ("EVAL: " ^ prReadableStr ast ^ "\n")
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else ()
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| NONE => ();
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eval' e ast)
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and eval' e (LIST (a::args,_)) = (case specialEval a of SOME special => special e args | _ => evalApply e (eval e a) args)
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| eval' e (SYMBOL s) = evalSymbol e s
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| eval' e (VECTOR (v,_)) = VECTOR (map (eval e) v, NO_META)
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| eval' e (MAP (m,_)) = MAP (List.map (fn (k, v) => (k, eval e v)) m, NO_META)
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| eval' e ast = ast
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and specialEval (SYMBOL "def!") = SOME evalDef
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| specialEval (SYMBOL "let*") = SOME evalLet
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| specialEval _ = NONE
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and evalDef e [SYMBOL s, ast] = let val v = eval e ast in (def s v e; v) end
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| evalDef _ _ = raise NotApplicable "def! needs a symbol and a form to evaluate"
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and evalLet e [LIST (bs,_), ast] = eval (bind bs (inside e)) ast
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| evalLet e [VECTOR (bs,_), ast] = eval (bind bs (inside e)) ast
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| evalLet _ _ = raise NotApplicable "let* needs a list of bindings and a form to evaluate"
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and evalApply e (FN (f,_)) args = f (map (eval e) args)
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| evalApply _ a args = raise NotApplicable (prStr a ^ " is not applicable on " ^ prStr (LIST (args, NO_META)))
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and evalSymbol e s = valOrElse (lookup e s)
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(fn _ => raise NotDefined ("symbol '" ^ s ^ "' not found"))
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and bind (SYMBOL s::v::rest) e = (def s (eval e v) e; bind rest e)
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| bind [] e = e
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| bind _ _ = raise NotApplicable "bindings must be a list of symbol/form pairs"
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fun print f =
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prReadableStr f
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fun rep e s =
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s |> read |> eval e |> print
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handle Nothing => ""
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| SyntaxError msg => "SYNTAX ERROR: " ^ msg
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| NotApplicable msg => "CANNOT APPLY: " ^ msg
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| NotDefined msg => "NOT DEFINED: " ^ msg
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fun malPlus (INT a, INT b) = INT (a + b)
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| malPlus _ = raise NotApplicable "can only add integers"
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fun malTimes (INT a, INT b) = INT (a * b)
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| malTimes _ = raise NotApplicable "can only multiply integers"
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fun malMinus (INT b, INT a) = INT (a - b)
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| malMinus _ = raise NotApplicable "can only subtract integers"
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fun malDiv (INT b, INT a) = INT (a div b)
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| malDiv _ = raise NotApplicable "can only divide integers"
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val replEnv = ENV (NS (ref [])) |> bind [
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SYMBOL "+",
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FN (foldl malPlus (INT 0), NO_META),
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SYMBOL "*",
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FN (foldl malTimes (INT 1), NO_META),
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SYMBOL "-",
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FN (fn [x] => malMinus (x, INT 0)
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| x::xs => foldr malMinus x xs
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| _ => raise NotApplicable "'-' requires arguments"
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, NO_META),
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SYMBOL "/",
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FN (fn [x] => malDiv (x, INT 1)
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| x::xs => foldr malDiv x xs
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| _ => raise NotApplicable "'/' requires arguments"
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, NO_META)
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]
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fun repl e =
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let open TextIO
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in (
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print("user> ");
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case inputLine(stdIn) of
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SOME(line) =>
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let val s = rep e line
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val _ = print(s ^ "\n")
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in
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repl e
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end
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| NONE => ()
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) end
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fun main () = repl replEnv
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