68 lines
1.9 KiB
Plaintext
68 lines
1.9 KiB
Plaintext
(* Little theory implementing the an assertion command in Isabelle/HOL. *)
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theory Assert
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imports Main
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keywords "assert" ::thy_decl
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begin
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ML{*
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(* Reimplementation needed because not exported from ML structure Value_Command *)
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fun value_maybe_select some_name =
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case some_name
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of NONE => Value_Command.value
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| SOME name => Value_Command.value_select name;
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(* Reimplementation structure Value_Command due to tiny modification of value_cmd. *)
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fun assert_cmd some_name modes raw_t state =
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let
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val ctxt = Toplevel.context_of state;
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val t = Syntax.read_term ctxt raw_t;
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val t' = value_maybe_select some_name ctxt t;
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val ty' = Term.type_of t';
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val ty' = case ty' of @{typ "bool"} => ty' | _ => error "Assertion expressions must be boolean.";
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val t' = case t' of @{term "True"} => t' | _ => error "Assertion failed.";
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val ctxt' = Variable.auto_fixes t' ctxt;
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val p = Print_Mode.with_modes modes (fn () =>
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Pretty.block [Pretty.quote (Syntax.pretty_term ctxt' t'), Pretty.fbrk,
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Pretty.str "::", Pretty.brk 1, Pretty.quote (Syntax.pretty_typ ctxt' ty')]) ();
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in Pretty.writeln p end;
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*}
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ML{*
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(* Reimplementation needed because not exported from ML structure Value_Command *)
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val opt_modes =
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Scan.optional (@{keyword "("} |-- Parse.!!! (Scan.repeat1 Parse.name --| @{keyword ")"})) [];
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(* Reimplementation needed because not exported from ML structure Value_Command *)
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val opt_evaluator =
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Scan.option (@{keyword "["} |-- Parse.name --| @{keyword "]"})
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(* NEW *)
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val _ =
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Outer_Syntax.command @{command_keyword assert} "evaluate and print term"
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(opt_evaluator -- opt_modes -- Parse.term
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>> (fn ((some_name, modes), t) => Toplevel.keep (assert_cmd some_name modes t) ));
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*}
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(* Test:
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assert ""
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assert "3 = 4"
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assert "False"
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assert "5 * 5 = 25 "
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*)
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assert "True \<and> True "
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assert "(5::int) * 5 = 25 "
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end
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