Add DRAWL page

README.md

@@ -4,7 +4,9 @@
 
 [Change List](https://github.com/dschmenk/PLASMA/blob/master/doc/Version%202.1.md#changes-in-plasma-for-211-release)
 
-[Get single boot floppy of FORTH for PLASMA 2.11](https://github.com/dschmenk/PLASMA/blob/master/images/apple/PLFORTH.PO)
+[FORTH implemented in PLASMA](https://github.com/dschmenk/PLASMA/blob/master/doc/PLFORTH.md)
+
+[LISP 1.5 implemented in PLASMA](https://github.com/dschmenk/PLASMA/blob/master/doc/DRAWL.md)
 
 # The PLASMA Programming Language
 

doc/DRAWL.md

@@ -0,0 +1,32 @@
+# LISP 1.5 implemented in PLASMA. LISP interpreted in a bytecode VM runnin on a 1 MHz 6502 is going to be sssllllooooowwwww. So I called this implementation DRAWL in keeping with the speech impediment theme.
+
+DRAWL represents an exploration REPL language for the PLASMA environment.
+
+It isn't meant to be a full-blown programming language, more of an interactive sandbox for playing with S-expressions.
+
+## Missing features of LISP 1.5 in DRAWL
+
+- The PROG feature isn't present. Programming is limited to interpreting lambda S-expressions
+- Number values are limited to 32 bit integera, no floating point
+- Deep recursion. The 6502 architecture limits recursion, so don't expect too much here
+
+However, the code is partitioned to allow for easy extension so some of these missing features could be implemented.
+
+## Features of DRAWL
+
+- 32 bit integers. Hey, better than you probably expected
+- Recursion handles about nine levels deep. Better than nothing
+- Fully garbage collected behind the scenes
+- Optionally read LISP source file at startup
+
+LISP is one of the earliest computer languages. As such, it holds a special place in the anals of computer science. I've always wanted to learn why LISP is held in such high regard by so many, so I went about learning LISP by actually implementing a LISP interpreter in PLASMA. PLASMA is well suited to implement other languages due to its rich syntax, performance and libraries.
+
+## Links
+
+Here are some links to get you started.
+
+LISP 1.5 Manual: https://archive.org/details/bitsavers_mitrlelisprammersManual2ed1985_9279667
+
+Video showing DRAWL in action:
+
+Preconfigured PLASMA ProDOS boot floppy for DRAWL: https://github.com/dschmenk/PLASMA/blob/master/images/apple/DRAWL.po

src/lisp/s-expr.pla

@@ -338,12 +338,8 @@ end
 
 def is_int(c); return c >= '0' and c <= '9'; end
 
-def is_alpha(c)
-  return c >= 'A' and c <= 'z'
-end
-
 def is_alphasym(c)
-  return c >= '0' and c <= 'z'
+  return (c >= '*' and c <= 'z') and (c <> '.') and (c <> ',')
 end
 
 def parse_int(evalptr)#2 // return evalptr, intptr
@@ -439,9 +435,9 @@ export def parse_expr(evalptr, level, refill)#2 // return evalptr, exprptr
         elemptr = NULL
         break
       otherwise
-        if (^evalptr == '-' and is_int(^(evalptr+1))) or is_int(^evalptr)
+        if is_int(^evalptr) or (^evalptr == '-' and is_int(^(evalptr+1)))
           evalptr, elemptr = parse_int(evalptr)
-        elsif is_alpha(^evalptr)
+        elsif is_alphasym(^evalptr)
           evalptr, elemptr = parse_sym(evalptr)
         else
           putc('\\')

src/mklisp

@@ -22,3 +22,4 @@ cat lisp/set.lisp                  | ./ac.jar -ptx DRAWL.po lisp/SET.LISP TXT
 cat lisp/list.lisp                 | ./ac.jar -ptx DRAWL.po lisp/LIST.LISP TXT
 cat lisp/maplist.lisp              | ./ac.jar -ptx DRAWL.po lisp/MAPLIST.LISP TXT
 cat lisp/gcd.lisp                  | ./ac.jar -ptx DRAWL.po lisp/GCD.LISP TXT
+cat lisp/fact.lisp                 | ./ac.jar -ptx DRAWL.po lisp/FACT.LISP TXT

src/mkrel

@@ -182,6 +182,7 @@ cp lisp/set.lisp          prodos/bld/lisp/SET.LISP.TXT
 cp lisp/list.lisp         prodos/bld/lisp/LIST.LISP.TXT
 cp lisp/maplist.lisp      prodos/bld/lisp/MAPLIST.LISP.TXT
 cp lisp/gcd.lisp          prodos/bld/lisp/GCD.LISP.TXT
+cp lisp/fact.lisp         prodos/bld/lisp/FACT.LISP.TXT
 
 #mkdir prodos/bld/examples
 #cp samplesrc/examples/ex.1.pla  prodos/bld/examples/EX.1.PLA.TXT