GSI(1) USER COMMANDS GSI(1) NAME gsi - Gambit Scheme interpreter SYNTAX gsi [expression]... DESCRIPTION Gsi is a Scheme interpreter that can be used to develop and debug Gambit Scheme programs. Gsi has the ability to dynam- ically load .O files produced by the Gambit Scheme compiler gsc. If expressions are passed as arguments to gsi, they are evaluated in left to right order and the result is printed on standard output. When no expressions appear on the command line, a read-eval-print (REP) loop is entered after having loaded the file ".init.scm" if it is present, otherwise "~/.init.scm" if it is present. READ EVAL PRINT LOOP INTERACTION In general, Scheme expressions typed in a REP loop are evaluated and the result printed out. When an evaluation error occurs, a REP loop of a higher level is entered. An end of file (^D) will cause the current REP loop to be aborted and the previous REP loop will be resumed. As opposed to most other Lisp systems, gsi combines the stan- dard REP loop functions with those of the debugger. In a sense, you are always in debugging mode. You can at all times examine the frames in the REP loop's continuation. This is useful to determine what part of the program sig- naled the error. Also, an expression typed in to the REP loop will be evaluated in the context of the frame currently being examined. Special commands accepted in a REP loop are: ,q Terminate gsi abruptly. ,t Return to outer most (oldest) REP loop. ,d Return to previous REP loop. Same as ^D. ,r expr Return from REP loop with the value of expr. This can also be used to resume a computation that was inter- rupted by the user (in this case expr can be any value). ,? Give summary of commands. ,+ or ,- Move to next or previous frame of the continuation. , Move to particular frame of the continuation. Frames are numbered with non-positive integers. Frame 0 is Amiga Release 2.04 Last change: local 1 GSI(1) USER COMMANDS GSI(1) the most recent. Frame -1 is the next to most recent and so on. When it is different from 0, the frame number appears in the prompt after the REP loop level. ,b Display a summary of each frame in the continuation starting with the current frame. There are 3 columns. The first is the frame number. The second is the pro- cedure that created the frame (and where control will return when control returns to this frame). The last column, if it is present, is the expression whose value is being computed. A frame created by a compiled pro- cedure has a third column only if the procedure was compiled with the DEBUG option. ,l List all non-global variables accessible from this frame. ,p Pretty print the procedure that created the current frame. NOTE At any moment, execution can be interrupted by typing the interrupt character (usually ^C). A program linked (by glk) with the full runtime library can call up a REP loop by evaluating `(##read-eval-print)'. OPTIONS The global variable `##argv' is bound to a vector of the arguments passed to the program. The following options are accepted by the program. -s stack size Override the default stack size. -c constant space size Override the default constant space size. -h heap size Override the default heap size. -d level Generate a trace of the steps performed when files are loaded. A level of 1 gives a summary of the steps while a level of 2 gives a full trace. If not specified, level defaults to 1. -v variable Prints out the value of the variable before starting the execution. This is mainly used to print the address of primi- tives when debugging. -p Generate a timing profile graph for every procedure bound to a global variable. The graph will be generated in the file prog.stats. DIAGNOSTICS The diagnostic messages produced by gsi are printed on the standard output file. Amiga Release 2.04 Last change: local 2