include term-colours.4th
include defer-is.4th
+\ ------ Types ------
+
0 constant number-type
1 constant boolean-type
2 constant character-type
-3 constant nil-type
-4 constant pair-type
+3 constant string-type
+4 constant nil-type
+5 constant pair-type
+6 constant symbol-type
: istype? ( obj -- obj b )
over = ;
+\ ------ Memory ------
+
100 constant N
create car-cells N allot
create car-type-cells N allot
cdr-type-cells + @
;
+: nil 0 nil-type ;
+
+: objvar create 0 , 0 , ;
+
+: value@ ( objvar -- val ) @ ;
+: type@ ( objvar -- type ) 1+ @ ;
+: value! ( newval objvar -- ) ! ;
+: type! ( newtype objvar -- ) 1+ ! ;
+: setobj ( newobj objvar -- ) dup rot swap 1+ ! ! ;
+: fetchobj ( objvar -- obj ) dup @ swap 1+ @ ;
+
+objvar symbol-table
+nil symbol-table setobj
\ ---- Read ----
: pair? ( -- bool )
nextchar [char] ( = ;
+: string? ( -- bool )
+ nextchar [char] " = ;
+
+: initial? ( -- bool )
+ nextchar [char] A >= nextchar [char] Z <= and if true exit then
+ nextchar [char] a >= nextchar [char] z <= and if true exit then
+ nextchar [char] * = if true exit then
+ nextchar [char] / = if true exit then
+ nextchar [char] > = if true exit then
+ nextchar [char] < = if true exit then
+ nextchar [char] = = if true exit then
+ nextchar [char] ? = if true exit then
+ nextchar [char] ! = if true exit then
+ false
+;
+
+: symbol? ( -- bool )
+ initial? if true exit then
+ nextchar [char] + =
+ nextchar [char] - = or if
+ inc-parse-idx
+ delim? if dec-parse-idx true exit then
+ dec-parse-idx
+ then
+ false
+;
: readnum ( -- num-atom )
minus? dup if
inc-parse-idx
;
+: readstring ( -- charlist )
+ nextchar [char] " = if
+ inc-parse-idx
+
+ delim? false = if
+ bold fg red
+ ." No delimiter following right double quote. Aborting." cr
+ reset-term abort
+ then
+
+ dec-parse-idx
+
+ 0 nil-type exit
+ then
+
+ nextchar [char] \ = if
+ inc-parse-idx
+ nextchar case
+ [char] n of '\n' endof
+ [char] " of [char] " endof
+ [char] \
+ endcase
+ else
+ nextchar
+ then
+ inc-parse-idx character-type
+
+ recurse
+
+ cons
+;
+
+: readsymbol ( -- charlist )
+ delim? if nil exit then
+
+ nextchar inc-parse-idx character-type
+
+ recurse
+
+ cons
+;
+
defer read
: readpair ( -- obj )
exit
then
+ string? if
+ inc-parse-idx
+ readstring
+ drop string-type
+
+ nextchar [char] " <> if
+ bold red ." Missing closing double-quote." reset-term cr
+ abort
+ then
+
+ inc-parse-idx
+ exit
+ then
+
+ symbol? if
+ readsymbol
+ drop symbol-type
+ 2dup
+ symbol-table fetch
+ cons
+ symbol-table set
+ exit
+ then
+
pair? if
inc-parse-idx
\ ---- Eval ----
: self-evaluating? ( obj -- obj bool )
- number-type istype? if true exit then
- boolean-type istype? if true exit then
- character-type istype? if true exit then
- nil-type istype? if true exit then
- false ;
+ true \ everything self-evaluating for now
+;
: eval
- \ self-evaluating? if
- \ exit
- \ then
- exit
+ self-evaluating? if
+ exit
+ then
bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
abort
endcase
;
+: (printstring) ( stringobj -- )
+ nil-type istype? if 2drop exit then
+
+ 2dup car drop dup
+ case
+ '\n' of ." \n" drop endof
+ [char] \ of ." \\" drop endof
+ [char] " of [char] \ emit [char] " emit drop endof
+ emit
+ endcase
+
+ cdr recurse
+;
+: printstring ( stringobj -- )
+ [char] " emit
+ (printstring)
+ [char] " emit ;
+
+: printsymbol ( symbolobj -- )
+ nil-type istype? if 2drop exit then
+
+ 2dup car drop emit
+ cdr recurse
+;
+
: printnil ( nilobj -- )
- drop ." ()" ;
+ 2drop ." ()" ;
defer print
: printpair ( pairobj -- )
2dup
car print
cdr
- nil-type istype? if 2drop ." )" exit then
+ nil-type istype? if 2drop exit then
pair-type istype? if space recurse exit then
." . " print
;
number-type istype? if printnum exit then
boolean-type istype? if printbool exit then
character-type istype? if printchar exit then
+ string-type istype? if printstring exit then
+ symbol-type istype? if printsymbol exit then
nil-type istype? if printnil exit then
pair-type istype? if ." (" printpair ." )" exit then