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32 lines
947 B
Prolog
32 lines
947 B
Prolog
% -*- mode: prolog; -*- select prolog mode in the emacs text editor
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:- format_predicate('V', env_format(_Arg,_Env)).
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env(mal_env(Assoc, t)) :- empty_assoc(Assoc).
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env(Outer, mal_env(Assoc, Outer)) :- empty_assoc(Assoc).
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env_get(mal_env(Assoc, _), Key, Value) :- get_assoc(Key, Assoc, Value).
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env_get(mal_env(_, Outer), Key, Value) :- env_get(Outer, Key, Value).
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env_set(Env, Key, Value) :-
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Env = mal_env(Old, _),
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put_assoc(Key, Old, Value, New),
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setarg(1, Env, New).
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env_format(_Arg, mal_env(Assoc, _Outer)) :-
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assoc_to_list(Assoc, Pairs),
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maplist(env_format_pair, Pairs).
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env_format_pair(K - V) :- format(" ~a:~F", [K, V]).
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% Does *not* check that the keys are symbols. This is done once when
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% the fn* structure is created.
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env_bind(_Env, [], []).
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env_bind(Env, ['&', K], Vs) :- !,
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list(Vs, List),
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env_set(Env, K, List).
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env_bind(Env, [K | Ks], [V | Vs]) :-
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env_set(Env, K, V),
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env_bind(Env, Ks, Vs).
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