Returns a constructed list in which the last element of U is followed by the first element of V. The list U is copied, V is not.

EXPR PROCEDURE APPEND(U, V);

IF	NULL U THEN V

ELSE CAR U . APPEND(CDR U, V);

If U occurs as the CAR portion of an element of the alist V, the dotted-pair in which U occurred is returned, else NIL is returned. ASSOC might not detect a poorly formed alist so an invalid construction may be detected by CAR or CDR.

EXPR PROCEDURE ASSOC(U, V);

IF	NULL V THEN NIL

ELSE

IF ATOM CAR V THEN

ERROR(000, LIST(V, "is a poorly formed alist"))

ELSE IF U = CAAR V THEN CAR V

ELSE ASSOC(U, CDR V);

A ”dlist” is a list in which each element is a two element list: (ID:id PROP:any). Each ID in U has the indicator IND with property PROP placed on its property list by the PUT function. The value of DEFLIST is a list of the first elements of each two element list. Like PUT, DEFLIST may not be used to define functions.

EXPR PROCEDURE DEFLIST(U, IND);

IF NULL U THEN NIL

ELSE <<

PUT(CAAR U, IND, CADAR U);

CAAR U >> . DEFLIST(CDR U, IND);

Returns V with the first top level occurrence of U removed from it.

EXPR PROCEDURE DELETE(U, V);

IF NULL V THEN NIL

ELSE IF CAR V = U THEN CDR V

ELSE CAR V . DELETE(U, CDR V);

Returns T if U is a digit, otherwise NIL.

EXPR PROCEDURE DIGIT(U);

IF MEMQ(U, ’(!0 !1 !2 !3 !4 !5 !6 !7 !8 !9))

THEN T ELSE NIL;

The top level length of the list X is returned.

EXPR PROCEDURE LENGTH(X);

IF ATOM X THEN 0

ELSE PLUS(1, LENGTH CDR X);

Returns T if U is a character of the alphabet, NIL otherwise.^a

EXPR PROCEDURE LITER(U);

IF

MEMQ(U, ’(

!A !B !C !D !E !F !G !H !I !J !K !L !M

!N !O !P !Q !R !S !T !U !V !W !X !Y !Z

!a !b !c !d !e !f !g !h !i !j !k !l !m

!n !o !p !q !r !s !t !u !v !w !x !y !z))

THEN T ELSE NIL;

Returns NIL if A is not a member of list B, returns the remainder of B whose first element is A.

EXPR PROCEDURE MEMBER(A, B);

IF NULL B THEN NIL

ELSE IF A = CAR B THEN B

ELSE MEMBER(A, CDR B);

Same as MEMBER but an EQ check is used for comparison.

EXPR PROCEDURE MEMQ(A, B);

IF	NULL B THEN NIL

ELSE IF A EQ CAR B THEN B

ELSE MEMQ(A, CDR B);

Concatenates V to U without copying U. The last CDR of U is modified to point to V.

EXPR PROCEDURE NCONC(U, V);

BEGIN SCALAR W;

IF NULL U THEN RETURN V;

W := U;

WHILE CDR W DO W := CDR W;

RPLACD(W, V);

RETURN U

END;

U and V are lists which must have an identical number of elements. If not, an error occurs (the 000 used in the ERROR call is arbitrary and need not be adhered to). Returned is a list where each element is a dotted-pair, the CAR of the pair being from U, and the CDR the corresponding element from V.

EXPR PROCEDURE PAIR(U, V);

IF AND(U, V) THEN (CAR U . CAR V) . PAIR(CDR U, CDR V)

ELSE IF OR(U, V) THEN ERROR(000,

"Different length lists in PAIR")

ELSE NIL;

Returns a copy of the top level of U in reverse order.

EXPR PROCEDURE REVERSE(U);

BEGIN SCALAR W;

WHILE U DO <<

W := CAR U . W;

U := CDR U >>;

RETURN W

END;

Searches the alist V for an occurrence of U. If U is not in the alist the evaluation of function FN is returned.

EXPR PROCEDURE SASSOC(U, V, FN);

IF NULL V THEN FN()

ELSE IF U = CAAR V THEN CAR V

ELSE SASSOC(U, CDR V, FN);

The value returned is the result of substituting the CDR of each element of the alist X for every occurrence of the CAR part of that element in Y.

EXPR PROCEDURE SUBLIS(X, Y);

IF NULL X THEN Y

ELSE BEGIN

SCALAR U;

U := ASSOC(Y, X);

RETURN

IF U THEN CDR U

ELSE IF ATOM Y THEN Y

ELSE

SUBLIS(X, CAR Y) .

SUBLIS(X, CDR Y)

END;

The value returned is the result of substituting U for all occurrences of V in W.

EXPR PROCEDURE SUBST(U, V, W);

IF NULL W THEN NIL

ELSE IF V = W THEN U

ELSE IF ATOM W THEN W

ELSE SUBST(U, V, CAR W) . SUBST(U, V, CDR W);