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36 lines
980 B
Forth
36 lines
980 B
Forth
3 years ago
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// identificatori
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type ide = string
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type aexp =
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| AEint of int
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| AEplus of (aexp * aexp)
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| AEminus of (aexp * aexp)
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| AElet of (ide * aexp * aexp)
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| AEide of ide
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let rec aexp_to_string : aexp -> string =
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fun e ->
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match e with
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AEint i -> sprintf "%d" i
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| AEplus (e,f) -> sprintf "(%s + %s)" (aexp_to_string e) (aexp_to_string f)
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| AEminus (e,f) -> sprintf "(%s - %s)" (aexp_to_string e) (aexp_to_string f)
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| AElet (x, e, f) ->
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Printf.sprintf "(let %s = %s in %s)" x (aexp_to_string e) (aexp_to_string f)
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| AEide (x) -> x
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// error handling
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let unbound_identifier_error ide =
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failwith (Printf.sprintf "unbound identifier %s" ide)
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// semantic domains
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type eval = int
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type dval = eval // denotable and expressible values coincide
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let eval_to_string : eval -> string =
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fun e -> Printf.sprintf "%d" e
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// ambiente
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type env = ide -> dval
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let empty = fun v -> unbound_identifier_error v
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