CHAPTER 1 FRANZ LISP 1.1. FRANZ LISP[|-] was created as a tool to further research in symbolic and algebraic manipulation, artificial intelligence, and programming languages at the University of California at Berkeley. Its roots are in a PDP-11 Lisp system which originally came from Harvard. As it grew it adopted features of Maclisp and Lisp Machine Lisp. Substantial compatibility with other Lisp dialects (Interlisp, UCILisp, CMULisp) is achieved by means of support packages and compiler switches. The heart of FRANZ LISP is written almost entirely in the programming language C. Of course, it has been greatly extended by additions written in Lisp. A small part is written in the assembly language for the current host machines, VAXen and a couple of flavors of 68000. Because FRANZ LISP is written in C, it is relatively portable and easy to comprehend. FRANZ LISP is capable of running large lisp pro- grams in a timesharing environment, has facilities for arrays and user defined structures, has a user con- trolled reader with character and word macro capabil- ities, and can interact directly with compiled Lisp, C, Fortran, and Pascal code. This document is a reference manual for the FRANZ LISP system. It is not a Lisp primer or introduction to the language. Some parts will be of interest pri- marily to those maintaining FRANZ LISP at their com- puter site. There is an additional document entitled _T_h_e _F_r_a_n_z _L_i_s_p _S_y_s_t_e_m, _b_y _J_o_h_n _F_o_d_e_r_a_r_o, _w_h_i_c_h _p_a_r_- _t_i_a_l_l_y _d_e_s_c_r_i_b_e_s _t_h_e _s_y_s_t_e_m _i_m_p_l_e_m_e_n_t_a_t_i_o_n. _F_R_A_N_Z _L_I_S_P, _a_s _d_e_l_i_v_e_r_e_d _b_y _B_e_r_k_e_l_e_y, _i_n_c_l_u_d_e_s _a_l_l _s_o_u_r_c_e _c_o_d_e _a_n_d _m_a_c_h_i_n_e _r_e_a_d_a_b_l_e _v_e_r_s_i_o_n _o_f _t_h_i_s _m_a_n_u_a_l _a_n_d _s_y_s_t_e_m _d_o_c_u_m_e_n_t. _T_h_e _s_y_s_t_e_m _d_o_c_u_m_e_n_t _i_s _i_n _a _s_i_n_g_l_e _f_i_l_e _n_a_m_e_d "_f_r_a_n_z._n" _i_n _t_h_e "_d_o_c" _s_u_b_d_i_r_e_c_t_o_r_y. ____________________ 9 [|-]It is rumored that this name has something to do with Franz Liszt [F_rants List] (1811-1886) a Hungarian composer and keyboard virtuoso. These allegations have never been proven. 9FRANZ LISP 1-1 FRANZ LISP 1-2 This document is divided into four Movements. In the first one we will attempt to describe the language of FRANZ LISP precisely and completely as it now stands (Opus 38.69, June 1983). In the second Move- ment we will look at the reader, function types, arrays and exception handling. In the third Movement we will look at several large support packages written to help the FRANZ LISP user, namely the trace package, compiler, fixit and stepping package. Finally the fourth movement contains an index into the other movements. In the rest of this chapter we shall exam- ine the data types of FRANZ LISP. The conventions used in the description of the FRANZ LISP functions will be given in 1.3 -- it is very important that these conventions are understood. 1.2. Data Types FRANZ LISP has fourteen data types. In this section we shall look in detail at each type and if a type is divisible we shall look inside it. There is a Lisp function _t_y_p_e which will return the type name of a lisp object. This is the official FRANZ LISP name for that type and we will use this name and this name only in the manual to avoid confus- ing the reader. The types are listed in terms of importance rather than alphabetically. 1.2.0. lispval This is the name we use to describe any Lisp object. The function _t_y_p_e will never return `lispval'. 1.2.1. symbol This object corresponds to a variable in most other programming languages. It may have a value or may be `unbound'. A symbol may be _l_a_m_b_d_a _b_o_u_n_d meaning that its current value is stored away somewhere and the symbol is given a new value for the duration of a certain context. When the Lisp processor leaves that context, the symbol's current value is thrown away and its old value is restored. 9 A symbol may also have a _f_u_n_c_t_i_o_n _b_i_n_d_i_n_g. This function binding is static; it cannot be lambda bound. Whenever the symbol is used in the func- tional position of a Lisp expression the function binding of the symbol is examined (see Chapter 4 for more details on evaluation). 9 A symbol may also have a _p_r_o_p_e_r_t_y _l_i_s_t, another Printed: January 31, 1984 FRANZ LISP 1-3 static data structure. The property list consists of a list of an even number of elements, considered to be grouped as pairs. The first element of the pair is the _i_n_d_i_c_a_t_o_r the second the _v_a_l_u_e of that indicator. 9 Each symbol has a print name (_p_n_a_m_e) which is how this symbol is accessed from input and referred to on (printed) output. 9 A symbol also has a hashlink used to link symbols together in the oblist -- this field is inaccessi- ble to the lisp user. 9 Symbols are created by the reader and by the func- tions _c_o_n_c_a_t, _m_a_k_n_a_m and their derivatives. Most symbols live on FRANZ LISP's sole _o_b_l_i_s_t, and therefore two symbols with the same print name are usually the exact same object (they are _e_q). Sym- bols which are not on the oblist are said to be _u_n_i_n_t_e_r_n_e_d. The function _m_a_k_n_a_m creates uninterned symbols while _c_o_n_c_a_t creates _i_n_t_e_r_n_e_d ones. 8 ____________________________________________________________ Subpart name Get value Set value Type 8 ________________________________________________________________________________________________________________________ value eval set lispval setq 8 ____________________________________________________________ property plist setplist list or nil list get putprop defprop 8 ____________________________________________________________ function getd putd array, binary, list binding def or nil 8 ____________________________________________________________ print name get_pname string 8 ____________________________________________________________ hash link 8 ____________________________________________________________ 7 |7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7| 1.2.2. list A list cell has two parts, called the car and cdr. List cells are created by the func- tion _c_o_n_s. 8 ________________________________________________ Subpart name Get value Set value Type 8 ________________________________________________________________________________________________ car car rplaca lispval 8 ________________________________________________ cdr cdr rplacd lispval 9 Printed: January 31, 1984 FRANZ LISP 1-4 8 ________________________________________________ 799 |99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777777777799 |99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777777777799 |99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777777777799 |99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777777777799 |99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 777777777777777777777777777777777777777777777 1.2.3. binary This type acts as a function header for machine coded functions. It has two parts, a pointer to the start of the function and a symbol whose print name describes the argument _d_i_s_c_i_p_l_i_n_e. The discipline (if _l_a_m_b_d_a, _m_a_c_r_o or _n_l_a_m_b_d_a) deter- mines whether the arguments to this function will be evaluated by the caller before this function is called. If the discipline is a string (specifi- cally "_s_u_b_r_o_u_t_i_n_e", "_f_u_n_c_t_i_o_n", "_i_n_t_e_g_e_r-_f_u_n_c_t_i_o_n", "_r_e_a_l-_f_u_n_c_t_i_o_n", "_c-_f_u_n_c_t_i_o_n", "_d_o_u_b_l_e-_c-_f_u_n_c_t_i_o_n", or "_v_e_c_t_o_r-_c-_f_u_n_c_t_i_o_n" ) then this function is a foreign subroutine or function (see 8.5 for more details on this). Although the type of the _e_n_t_r_y field of a binary type object is usually string or other, the object pointed to is actually a sequence of machine instructions. Objects of type binary are created by _m_f_u_n_c_t_i_o_n, _c_f_a_s_l, and _g_e_t_a_d_d_r_e_s_s. 8 _________________________________________________________ Subpart name Get value Set value Type 8 __________________________________________________________________________________________________________________ entry getentry string or fixnum 8 _________________________________________________________ discipline getdisc putdisc symbol or fixnum 8 _________________________________________________________ 7 |8|7|7|7|7| 9 |8|7|7|7|7| 9 |8|7|7|7|7| 9 |8|7|7|7|7| 9 |8|7|7|7|7| 9 1.2.4. fixnum A fixnum is an integer constant in the range -2[31] to 2[31]-1. Small fixnums (-1024 to 1023) are stored in a special table so they needn't be allocated each time one is needed. In principle, the range for fixnums is machine depen- dent, although all current implementations for franz have this range. 1.2.5. flonum A flonum is a double precision real number. On the VAX, the range is +_2.9x10[-37] to +_1.7x10[38]. There are approximately sixteen decimal digits of precision. Other machines may have other ranges. 9 Printed: January 31, 1984 FRANZ LISP 1-5 1.2.6. bignum A bignum is an integer of potentially unbounded size. When integer arithmetic exceeds the limits of fixnums mentioned above, the calcula- tion is automatically done with bignums. Should calculation with bignums give a result which can be represented as a fixnum, then the fixnum represen- tation will be used[|-]. This contraction is known as _i_n_t_e_g_e_r _n_o_r_m_a_l_i_z_a_t_i_o_n. Many Lisp functions assume that integers are normalized. Bignums are composed of a sequence of list cells and a cell known as an sdot. The user should consider a big- num structure indivisible and use functions such as _h_a_i_p_a_r_t, and _b_i_g_n_u_m-_l_e_f_t_s_h_i_f_t to extract parts of it. 1.2.7. string A string is a null terminated sequence of characters. Most functions of symbols which operate on the symbol's print name will also work on strings. The default reader syntax is set so that a sequence of characters surrounded by dou- ble quotes is a string. 1.2.8. port A port is a structure which the system I/O routines can reference to transfer data between the Lisp system and external media. Unlike other Lisp objects there are a very limited number of ports (20). Ports are allocated by _i_n_f_i_l_e and _o_u_t_- _f_i_l_e and deallocated by _c_l_o_s_e and _r_e_s_e_t_i_o. The _p_r_i_n_t function prints a port as a percent sign fol- lowed by the name of the file it is connected to (if the port was opened by _f_i_l_e_o_p_e_n, _i_n_f_i_l_e, _o_r _o_u_t_f_i_l_e). During initialization, FRANZ LISP binds the symbol piport to a port attached to the stan- dard input stream. This port prints as %$stdin. There are ports connected to the standard output and error streams, which print as %$stdout and %$stderr. This is discussed in more detail at the beginning of Chapter 5. ____________________ 9 [|-]The current algorithms for integer arithmetic opera- tions will return (in certain cases) a result between +_2[30] and 2[31] as a bignum although this could be represented as a fixnum. 9 Printed: January 31, 1984 FRANZ LISP 1-6 1.2.9. vector Vectors are indexed sequences of data. They can be used to implement a notion of user-defined types via their associated property list. They make hunks (see below) logically unnecessary, although hunks are very efficiently garbage collected. There is a second kind of vec- tor, called an immediate-vector, which stores binary data. The name that the function _t_y_p_e returns for immediate-vectors is vectori. Immediate-vectors could be used to implement strings and block-flonum arrays, for example. Vec- tors are discussed in chapter 9. The functions _n_e_w-_v_e_c_t_o_r, and _v_e_c_t_o_r, can be used to create vec- tors. 8 ________________________________________________ Subpart name Get value Set value Type 8 ________________________________________________________________________________________________ datum[_i] vref vset lispval 8 ________________________________________________ property vprop vsetprop lispval vputprop 8 ________________________________________________ size vsize - fixnum 8 ________________________________________________ 7 |7|7|7|7|7|7|7| |7|7|7|7|7|7|7| |7|7|7|7|7|7|7| |7|7|7|7|7|7|7| |7|7|7|7|7|7|7| 1.2.10. array Arrays are rather complicated types and are fully described in Chapter 9. An array consists of a block of contiguous data, a function to access that data, and auxiliary fields for use by the accessing function. Since an array's accessing function is created by the user, an array can have any form the user chooses (e.g. n- dimensional, triangular, or hash table). Arrays are created by the function _m_a_r_r_a_y. 8 _______________________________________________________________ Subpart name Get value Set value Type 8 ______________________________________________________________________________________________________________________________ access function getaccess putaccess binary, list or symbol 8 _______________________________________________________________ auxiliary getaux putaux lispval 8 _______________________________________________________________ data arrayref replace block of contiguous set lispval 8 _______________________________________________________________ length getlength putlength fixnum 8 _______________________________________________________________ delta getdelta putdelta fixnum 9 Printed: January 31, 1984 FRANZ LISP 1-7 8 _______________________________________________________________ 799 |9|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777899 |9|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777899 |9|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777899 |9|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 7777777777777777777777777777777777777777899 |9|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99|99| 777777777777777777777777777777777777778 1.2.11. value A value cell contains a pointer to a lispval. This type is used mainly by arrays of general lisp objects. Value cells are created with the _p_t_r function. A value cell containing a pointer to the symbol `foo' is printed as `(ptr to)foo' 1.2.12. hunk A hunk is a vector of from 1 to 128 lispvals. Once a hunk is created (by _h_u_n_k or _m_a_k_h_u_n_k) it cannot grow or shrink. The access time for an element of a hunk is slower than a list cell element but faster than an array. Hunks are really only allocated in sizes which are powers of two, but can appear to the user to be any size in the 1 to 128 range. Users of hunks must realize that (_n_o_t (_a_t_o_m '_l_i_s_p_v_a_l)) will return true if _l_i_s_p_v_a_l is a hunk. Most lisp systems do not have a direct test for a list cell and instead use the above test and assume that a true result means _l_i_s_p_v_a_l is a list cell. In FRANZ LISP you can use _d_t_p_r to check for a list cell. Although hunks are not list cells, you can still access the first two hunk ele- ments with _c_d_r and _c_a_r and you can access any hunk element with _c_x_r[|-]. You can set the value of the first two elements of a hunk with _r_p_l_a_c_d and _r_p_l_a_c_a and you can set the value of any element of the hunk with _r_p_l_a_c_x. A hunk is printed by printing its contents surrounded by { and }. However a hunk cannot be read in in this way in the standard lisp system. It is easy to write a reader macro to do this if desired. 1.2.13. other Occasionally, you can obtain a pointer to storage not allocated by the lisp sys- tem. One example of this is the entry field of those FRANZ LISP functions written in C. Such objects are classified as of type other. Foreign functions which call malloc to allocate their own space, may also inadvertantly create such objects. The garbage collector is supposed to ignore such ____________________ 9 [|-]In a hunk, the function _c_d_r references the first ele- ment and _c_a_r the second. Printed: January 31, 1984 FRANZ LISP 1-8 objects. 1.3. Documentation The conventions used in the follow- ing chapters were designed to give a great deal of information in a brief space. The first line of a function description contains the function name in bold face and then lists the arguments, if any. The arguments all have names which begin with a letter or letters and an underscore. The letter(s) gives the allowable type(s) for that argument according to this table. 8 _______________________________________________________ Letter Allowable type(s) 8 ______________________________________________________________________________________________________________ g any type 8 _______________________________________________________ s symbol (although nil may not be allowed) 8 _______________________________________________________ t string 8 _______________________________________________________ l list (although nil may be allowed) 8 _______________________________________________________ n number (fixnum, flonum, bignum) 8 _______________________________________________________ i integer (fixnum, bignum) 8 _______________________________________________________ x fixnum 8 _______________________________________________________ b bignum 8 _______________________________________________________ f flonum 8 _______________________________________________________ u function type (either binary or lambda body) 8 _______________________________________________________ y binary 8 _______________________________________________________ v vector 8 _______________________________________________________ V vectori 8 _______________________________________________________ a array 8 _______________________________________________________ e value 8 _______________________________________________________ p port (or nil) 8 _______________________________________________________ h hunk 8 _______________________________________________________ 7 |7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7| |7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7|7| In the first line of a function description, those arguments preceded by a quote mark are evaluated (usu- ally before the function is called). The quoting con- vention is used so that we can give a name to the result of evaluating the argument and we can describe the allowable types. If an argument is not quoted it does not mean that that argument will not be 9 Printed: January 31, 1984 FRANZ LISP 1-9 evaluated, but rather that if it is evaluated, the time at which it is evaluated will be specifically mentioned in the function description. Optional argu- ments are surrounded by square brackets. An ellipsis (...) means zero or more occurrences of an argument of the directly preceding type. 9 9 Printed: January 31, 1984