LISP I Programmer's Manual - Software Preservation Group

eturn[fn[a]In terms of the M-type notation introduced in the previoussection this becomes:compiler program for search[~,p,fn,u] with programvariable at:at = LTEST [null[at] -+ -+ return[u];p[at]at = cdr[at]go [ TEST 1I]-In writing programs for the compiler the function setq mustbe used ---set is not acceptable.Amplification of the compiler system is under way. Inparticular a feature will be included to permit a user to writeSAP-type programs defining functions. Such programs will representa third way (in addition to EXPR and SUBR) of definingfunctions on their association lists, and should add flexibilityto the system. SAP-program definitions of functions w i l l betermed tMacros' and will be described in a later memo.Two examples of compiled functions are given below.1) memlis[x;y]The function memlis[x;y] is a predicate whose value is trueif x is a member of the list y, and false otherwise. x can bean atomic symbol or a list.In the program below the compiler has generated certainatomic symbols (~0005, G0006, G0008, ~0009) as location referencesin the program, and other symbols to be used as temporarystorage as indicated below.G0001) Index Register 4 at entry to memlis subroutineG0002) Storage for xG0003) Storage for yG0004) Storage for final answer (true or false)