src/HOL/Spec_Check/Examples.thy

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theory Examples
imports Spec_Check
begin

section {* List examples *}

ML_command {*
check_property "ALL xs. rev xs = xs";
*}

ML_command {*
check_property "ALL xs. rev (rev xs) = xs";
*}


section {* AList Specification *}

ML_command {*
(* map_entry applies the function to the element *)
check_property "ALL k f xs. AList.lookup (op =) (AList.map_entry (op =) k f xs) k = Option.map f (AList.lookup (op =) xs k)";
*}

ML_command {*
(* update always results in an entry *)
check_property "ALL k v xs. AList.defined (op =) (AList.update (op =) (k, v) xs) k";
*}

ML_command {*
(* update always writes the value *)
check_property "ALL k v xs. AList.lookup (op =) (AList.update (op =) (k, v) xs) k = SOME v";
*}

ML_command {*
(* default always results in an entry *)
check_property "ALL k v xs. AList.defined (op =) (AList.default (op =) (k, v) xs) k";
*}

ML_command {*
(* delete always removes the entry *)
check_property "ALL k xs. not (AList.defined (op =) (AList.delete (op =) k xs) k)";
*}

ML_command {*
(* default writes the entry iff it didn't exist *)
check_property "ALL k v xs. (AList.lookup (op =) (AList.default (op =) (k, v) xs) k = (if AList.defined (op =) xs k then AList.lookup (op =) xs k else SOME v))";
*}

section {* Examples on Types and Terms *}

ML_command {*
check_property "ALL f g t. map_types (g o f) t = (map_types f o map_types g) t";
*}

ML_command {*
check_property "ALL f g t. map_types (f o g) t = (map_types f o map_types g) t";
*}


text {* One would think this holds: *}

ML_command {*
check_property "ALL t ts. strip_comb (list_comb (t, ts)) = (t, ts)"
*}

text {* But it only holds with this precondition: *}

ML_command {*
check_property "ALL t ts. case t of _ $ _ => true | _ => strip_comb (list_comb (t, ts)) = (t, ts)"
*}

section {* Some surprises *}

ML_command {*
check_property "ALL Ts t. type_of1 (Ts, t) = fastype_of1 (Ts, t)"
*}


ML_command {*
val thy = @{theory};
check_property "ALL t u. if Pattern.matches thy (t, u) then Term.could_unify (t, u) else true"
*}

end