4 constant nil-type
5 constant pair-type
6 constant symbol-type
-: istype? ( obj -- obj b )
+: istype? ( obj type -- obj bool )
over = ;
\ ------ Memory ------
-100 constant N
+1000 constant N
create car-cells N allot
create car-type-cells N allot
create cdr-cells N allot
cdr-type-cells + @
;
+: caar car car ;
+: cadr cdr car ;
+: cdar car cdr ;
+: cddr cdr cdr ;
+
: nil 0 nil-type ;
+: nil? nil-type istype? ;
: objvar create 0 , 0 , ;
objvar symbol-table
nil symbol-table setobj
+: objeq? ( obj obj -- bool )
+ rot = -rot = and ;
+
+\ ---- Pre-defined symbols ----
+
+: (create-symbol) ( addr n -- symbol-obj )
+ dup 0= if
+ 2drop nil
+ else
+ 2dup drop @ character-type 2swap
+ swap 1+ swap 1-
+ recurse
+
+ cons
+ then
+;
+
+: create-symbol ( -- )
+ bl word
+ count
+
+ (create-symbol)
+ drop symbol-type
+
+ 2dup
+
+ symbol-table fetchobj
+ cons
+ symbol-table setobj
+
+ create swap , ,
+ does> dup @ swap 1+ @
+;
+
+create-symbol quote quote
+
\ ---- Read ----
variable parse-idx
: 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
cons
;
+: charlist-equiv ( charlist charlist -- bool )
+
+ 2over 2over
+
+ \ One or both nil
+ nil? -rot 2drop
+ if
+ nil? -rot 2drop
+ if
+ 2drop 2drop true exit
+ else
+ 2drop 2drop false exit
+ then
+ else
+ nil? -rot 2drop
+ if
+ 2drop 2drop false exit
+ then
+ then
+
+ 2over 2over
+
+ \ Neither nil
+ car drop -rot car drop = if
+ cdr 2swap cdr recurse
+ else
+ 2drop 2drop false
+ then
+;
+
+: charlist>symbol ( charlist -- symbol-obj )
+
+ symbol-table fetchobj
+
+ begin
+ nil? false =
+ while
+ 2over 2over
+ car drop pair-type
+ charlist-equiv if
+ 2swap 2drop
+ car
+ exit
+ else
+ cdr
+ then
+ repeat
+
+ 2drop
+ drop symbol-type 2dup
+ symbol-table fetchobj cons
+ symbol-table setobj
+;
+
defer read
-: readpair ( -- obj )
+: readpair ( -- pairobj )
eatspaces
\ Empty lists
exit
then
- symbol? if
- readsymbol
- drop symbol-type
- 2dup
- symbol-table fetch
- cons
- symbol-table set
- exit
- then
-
pair? if
inc-parse-idx
exit
then
+ nextchar [char] ' = if
+ inc-parse-idx
+ quote recurse nil cons cons exit
+ then
+
eof? if
bold fg blue ." Moriturus te saluto." reset-term ." ok" cr
quit
then
- bold fg red ." Error parsing string starting at character '"
- nextchar emit
- ." '. Aborting." reset-term cr
- abort
+ \ Anything else is assumed to be a symbol
+ readsymbol charlist>symbol
; is read
\ ---- Eval ----
: self-evaluating? ( obj -- obj bool )
- true \ everything self-evaluating for now
+ boolean-type istype? if true exit then
+ number-type istype? if true exit then
+ character-type istype? if true exit then
+ string-type istype? if true exit then
+ nil-type istype? if true exit then
+
+ false
;
+: tagged-list? ( obj tag-obj -- obj bool )
+ 2over
+ pair-type istype? false = if
+ 2drop 2drop false
+ else
+ car objeq?
+ then ;
+
+: quote? ( obj -- obj bool )
+ quote tagged-list? ;
+
+: quote-body ( quote-obj -- quote-body-obj )
+ cadr ;
+
: eval
self-evaluating? if
exit
then
+ quote? if
+ quote-body
+ exit
+ then
+
bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
abort
;