mirror of
https://github.com/kanaka/mal.git
synced 2024-11-11 00:52:44 +03:00
240 lines
8.2 KiB
Forth
240 lines
8.2 KiB
Forth
module REPL
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open System
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open Node
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open Types
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let rec iterPairs f = function
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| Pair(first, second, t) ->
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f first second
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iterPairs f t
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| Empty -> ()
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| _ -> raise <| Error.errExpectedX "list or vector"
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let quasiquoteForm nodes =
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let transformNode f = function
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| Elements 1 [|a|] -> f a
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| _ -> raise <| Error.wrongArity ()
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let singleNode = transformNode (fun n -> n)
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let rec quasiquote node =
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match node with
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| Cons(Symbol("unquote"), rest) -> rest |> singleNode
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| Cons(Cons(Symbol("splice-unquote"), spliceRest), rest) ->
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List([Symbol("concat"); singleNode spliceRest; quasiquote rest])
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| Cons(h, t) -> List([Symbol("cons"); quasiquote h; quasiquote t])
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| n -> List([Symbol("quote"); n])
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List(nodes) |> transformNode quasiquote
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let quoteForm = function
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| [node] -> node
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| _ -> raise <| Error.wrongArity ()
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let rec macroExpand env = function
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| Env.IsMacro env (Macro(_, f, _, _, _), rest) ->
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f rest |> macroExpand env
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| node -> node
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let rec eval_ast env = function
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| Symbol(sym) -> Env.get env sym
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| List(lst) -> lst |> List.map (eval env) |> List
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| Vector(seg) -> seg |> Seq.map (eval env) |> Array.ofSeq |> Node.ofArray
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| Map(map) -> map |> Map.map (fun k v -> eval env v) |> Map
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| node -> node
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and defBangForm env = function
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| [sym; form] ->
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match sym with
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| Symbol(sym) ->
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let node = eval env form
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Env.set env sym node
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node
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| _ -> raise <| Error.errExpectedX "symbol"
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| _ -> raise <| Error.wrongArity ()
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and defMacroForm env = function
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| [sym; form] ->
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match sym with
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| Symbol(sym) ->
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let node = eval env form
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match node with
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| Func(_, f, body, binds, outer) ->
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let node = Env.makeMacro f body binds outer
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Env.set env sym node
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node
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| _ -> raise <| Error.errExpectedX "user defined func"
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| _ -> raise <| Error.errExpectedX "symbol"
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| _ -> raise <| Error.wrongArity ()
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and macroExpandForm env = function
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| [form] -> macroExpand env form
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| _ -> raise <| Error.wrongArity ()
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and setBinding env first second =
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let s = match first with
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| Symbol(s) -> s
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| _ -> raise <| Error.errExpectedX "symbol"
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let form = eval env second
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Env.set env s form
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and letStarForm outer = function
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| [bindings; form] ->
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let inner = Env.makeNew outer [] []
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let binder = setBinding inner
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match bindings with
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| List(_) | Vector(_) -> iterPairs binder bindings
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| _ -> raise <| Error.errExpectedX "list or vector"
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inner, form
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| _ -> raise <| Error.wrongArity ()
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and ifForm env = function
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| [condForm; trueForm; falseForm] -> ifForm3 env condForm trueForm falseForm
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| [condForm; trueForm] -> ifForm3 env condForm trueForm Nil
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| _ -> raise <| Error.wrongArity ()
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and ifForm3 env condForm trueForm falseForm =
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match eval env condForm with
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| Bool(false) | Nil -> falseForm
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| _ -> trueForm
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and doForm env = function
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| [a] -> a
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| a::rest ->
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eval env a |> ignore
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doForm env rest
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| _ -> raise <| Error.wrongArity ()
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and fnStarForm outer nodes =
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let makeFunc binds body =
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let f = fun nodes ->
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let inner = Env.makeNew outer binds nodes
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eval inner body
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Env.makeFunc f body binds outer
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match nodes with
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| [List(binds); body] -> makeFunc binds body
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| [Vector(seg); body] -> makeFunc (List.ofSeq seg) body
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| [_; _] -> raise <| Error.errExpectedX "bindings of list or vector"
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| _ -> raise <| Error.wrongArity ()
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and catchForm env err = function
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| List([Symbol("catch*"); Symbol(_) as sym; catchBody]) ->
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let inner = Env.makeNew env [sym] [err]
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catchBody |> eval inner
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| List([_; _; _]) -> raise <| Error.argMismatch ()
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| _ -> raise <| Error.wrongArity ()
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and tryForm env = function
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| [exp; catchClause] ->
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try
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eval env exp
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with
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| Error.EvalError(str) -> catchForm env (String(str)) catchClause
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| Error.MalError(node) -> catchForm env node catchClause
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| _ -> raise <| Error.wrongArity ()
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and eval env = function
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| List(_) as node ->
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match macroExpand env node with
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| List(Symbol("def!")::rest) -> defBangForm env rest
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| List(Symbol("defmacro!")::rest) -> defMacroForm env rest
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| List(Symbol("macroexpand")::rest) -> macroExpandForm env rest
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| List(Symbol("let*")::rest) ->
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let inner, form = letStarForm env rest
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form |> eval inner
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| List(Symbol("if")::rest) -> ifForm env rest |> eval env
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| List(Symbol("do")::rest) -> doForm env rest |> eval env
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| List(Symbol("fn*")::rest) -> fnStarForm env rest
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| List(Symbol("quote")::rest) -> quoteForm rest
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| List(Symbol("quasiquote")::rest) -> quasiquoteForm rest |> eval env
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| List(Symbol("try*")::rest) -> tryForm env rest
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| List(_) as node ->
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let resolved = node |> eval_ast env
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match resolved with
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| List(BuiltInFunc(_, f)::rest) -> f rest
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| List(Func(_, _, body, binds, outer)::rest) ->
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let inner = Env.makeNew outer binds rest
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body |> eval inner
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| _ -> raise <| Error.errExpectedX "func"
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| node -> node
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| node -> node |> eval_ast env
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let READ input =
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try
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Reader.read_str input
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with
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| Error.ReaderError(msg) ->
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printfn "%s" msg
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[]
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let EVAL env ast =
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try
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Some(eval env ast)
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with
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| Error.EvalError(msg) ->
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printfn "%s" msg
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None
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let PRINT v =
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v
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|> Seq.singleton
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|> Printer.pr_str
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|> printfn "%s"
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let RE env input =
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READ input
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|> Seq.ofList
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|> Seq.choose (fun form -> EVAL env form)
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let REP env input =
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input
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|> RE env
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|> Seq.iter (fun value -> PRINT value)
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let getReadlineMode args =
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if args |> Array.exists (fun e -> e = "--raw") then
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Readline.Mode.Raw
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else
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Readline.Mode.Terminal
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let eval_func env = function
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| [ast] -> eval env ast
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| _ -> raise <| Error.wrongArity ()
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let argv_func = function
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| file::rest -> rest |> List.map Types.String |> Types.List
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| [] -> Types.List([])
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let configureEnv args =
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let env = Env.makeRootEnv ()
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Env.set env "eval" <| Env.makeBuiltInFunc (fun nodes -> eval_func env nodes)
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Env.set env "*ARGV*" <| argv_func args
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RE env """
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(def! not (fn* (a) (if a false true)))
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(def! load-file (fn* (f) (eval (read-string (slurp f)))))
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(defmacro! or (fn* (& xs) (if (empty? xs) nil (if (= 1 (count xs)) (first xs) `(let* (or_ ~(first xs)) (if or_ or_ (or ~@(rest xs))))))))
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(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw "odd number of forms to cond")) (cons 'cond (rest (rest xs)))))))
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""" |> Seq.iter ignore
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env
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[<EntryPoint>]
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let main args =
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let mode = getReadlineMode args
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let args = Seq.ofArray args |> Seq.filter (fun e -> e <> "--raw") |> List.ofSeq
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let env = configureEnv args
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match args with
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| file::_ ->
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System.IO.File.ReadAllText file
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|> REP env
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0
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| _ ->
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let rec loop () =
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match Readline.read "user> " mode with
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| null -> 0
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| input ->
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REP env input
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loop ()
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loop ()
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