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- -module(scheme_prelude).
- -export([cons/2, car/1, cdr/1, list_p/1]).
- % Scheme prelude for programs compiled from Scheme to Erlang.
- % A few conventions apply:
- % - question marks become _p, so even? becomes even_p
- % - exclamation marks are outlawed because the Scheme subset
- % is pure-functional, so set! and its ilk are not present.
- % - hyphens become _mn, so list-ref becomes list_mnref
- % - underscores will become double underscores.
- % At present, this still leaves an ambiguity between even-p and
- % even?, but we will ignore that. All that aside, operator
- % symbols become three-character abbreviations whose names all
- % begin with an underscore. For example:
- % + -> _pl
- % * -> _st
- % - -> _mn
- % / -> _dv
- % Therefore, symbols can still be used in variable names, such
- % as *some-variable* which becomes _stsome_mnvariable_st. This
- % would be hideous to work with, but for our purposes is
- % transparent enough.
- % variadic functions
- _pl([A]) -> A;
- _pl([A|B]) -> A + _pl(B).
- _st([A]) -> A;
- _st([A|B]) -> A * _st(B).
- _mn([A]) -> A;
- _mn([A|B]) -> A - _mn(B).
- list(L) -> L.
- _eq(A, B) -> A == B.
- cons(A, B) -> [A|B].
- car([A|_]) -> A.
- cdr([_|B]) -> B.
- append(A, B) -> lists:append(A, B).
- filter(Proc, L) -> lists:filter(Proc, L).
- map(Proc, L) -> lists:map(Proc, L).
- member(X, [X|L]) -> [X|L];
- member(X, [_|L]) -> member(X, L);
- member(_, []) -> false.
- assoc(X, [{X, A}|L]) -> {X, A};
- assoc(X, [{_, _}|L]) -> scheme_prelude:assoc(X, L);
- assoc(_, []) -> false.
- reverse(L) -> lists:reverse(L).
- reduce(Proc, [X|L]) -> lists:foldl(Proc, X, L).
- list_qs([_|B]) -> scheme_prelude:list_qs(B);
- list_qs([]) -> true;
- list_qs(_) -> false.
- null_qs([]) -> true;
- null_qs(_) -> false.
- pair_qs([_|_]) -> true;
- pair_qs(_) -> false.
- number_qs(X) -> is_number(X).
- equals_qs(X, Y) -> X == Y.
- length([X|Y]) -> 1 + scheme_prelude:length(Y);
- length([]) -> 0.
- symbol_qs(X) -> is_atom(X).
- boolean_qs(true) -> true.
- boolean_qs(false) -> true.
- boolean_qs(_) -> false.
- and(L) -> all(scheme_prelude:is_true, L).
- or(L) -> any(scheme_prelude:is_true, L).
- not(false) -> true;
- not(_) -> false.
- is_true(false) -> false;
- is_true(X) -> X.
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