include term-colours.4th
include defer-is.4th
+include float.4th
+
+include debugging.4th
+
+defer read
+defer eval
+defer print
\ ------ Types ------
-0 constant number-type
-1 constant boolean-type
-2 constant character-type
-3 constant string-type
-4 constant nil-type
-5 constant pair-type
-6 constant symbol-type
+variable nexttype
+0 nexttype !
+: make-type
+ create nexttype @ ,
+ 1 nexttype +!
+ does> @ ;
+
+make-type fixnum-type
+make-type realnum-type
+make-type boolean-type
+make-type character-type
+make-type string-type
+make-type nil-type
+make-type pair-type
+make-type symbol-type
+make-type primitive-proc-type
+make-type compound-proc-type
: istype? ( obj type -- obj bool )
over = ;
\ ------ Cons cell memory ------ {{{
-1000 constant N
-create car-cells N allot
-create car-type-cells N allot
-create cdr-cells N allot
-create cdr-type-cells N allot
+1000 constant scheme-memsize
+create car-cells scheme-memsize allot
+create car-type-cells scheme-memsize allot
+create cdr-cells scheme-memsize allot
+create cdr-type-cells scheme-memsize allot
+create nextfrees scheme-memsize allot
+:noname
+ scheme-memsize 0 do
+ i 1+ nextfrees i + !
+ loop
+; execute
+
variable nextfree
0 nextfree !
+: inc-nextfree
+ nextfrees nextfree @ + @
+
+ dup scheme-memsize < if
+ nextfree !
+ else
+ bold fg red
+ ." Out of memory! Aborting."
+ reset-term abort
+ then
+;
+
: cons ( car-obj cdr-obj -- pair-obj )
cdr-type-cells nextfree @ + !
cdr-cells nextfree @ + !
car-cells nextfree @ + !
nextfree @ pair-type
-
- 1 nextfree +!
+ inc-nextfree
;
: car ( pair-obj -- car-obj )
: type@ ( objvar -- type ) 1+ @ ;
: value! ( newval objvar -- ) ! ;
: type! ( newtype objvar -- ) 1+ ! ;
-: setobj ( newobj objvar -- ) dup rot swap 1+ ! ! ;
-: fetchobj ( objvar -- obj ) dup @ swap 1+ @ ;
+: obj! ( newobj objvar -- ) dup rot swap 1+ ! ! ;
+: obj@ ( objvar -- obj ) dup @ swap 1+ @ ;
: objeq? ( obj obj -- bool )
rot = -rot = and ;
\ }}}
+\ ---- Garbage Collection ---- {{{
+
+variable gc-enabled
+false gc-enabled !
+
+: gc-enable
+ true gc-enabled ! ;
+
+: gc-disable
+ false gc-enabled ! ;
+
+: gc-enabled?
+ gc-enabled @ ;
+
+: pairlike? ( obj -- obj bool )
+ pair-type istype? if true exit then
+ string-type istype? if true exit then
+ symbol-type istype? if true exit then
+ compound-proc-type istype? if true exit then
+
+ false
+;
+
+: pairlike-marked? ( obj -- obj bool )
+ over nextfrees + @ 0=
+;
+
+: mark-pairlike ( obj -- obj )
+ over nextfrees + 0 swap !
+;
+
+: gc-unmark ( -- )
+ scheme-memsize 0 do
+ 1 nextfrees i + !
+ loop
+;
+
+defer gc-mark-trace
+: gc-mark-obj ( obj -- )
+
+ gc-mark-trace
+
+ pairlike? invert if 2drop exit then
+ pairlike-marked? if 2drop exit then
+
+ mark-pairlike
+
+ drop pair-type 2dup
+
+ car recurse
+ cdr recurse
+;
+
+: gc-sweep
+ scheme-memsize nextfree !
+ 0 scheme-memsize 1- do
+ nextfrees i + @ 0<> if
+ nextfree @ nextfrees i + !
+ i nextfree !
+ then
+ -1 +loop
+;
+
+\ }}}
+
+
+
\ ---- Pre-defined symbols ---- {{{
objvar symbol-table
+: duplicate-charlist ( charlist -- copy )
+ 2dup nil objeq? false = if
+ 2dup car 2swap cdr recurse cons
+ then ;
+
+: 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 obj@
+
+ 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 obj@ cons
+ symbol-table obj!
+;
+
+
: (create-symbol) ( addr n -- symbol-obj )
dup 0= if
2drop nil
2dup
- symbol-table fetchobj
+ symbol-table obj@
cons
- symbol-table setobj
+ symbol-table obj!
create swap , ,
does> dup @ swap 1+ @
create-symbol set! set!-symbol
create-symbol ok ok-symbol
create-symbol if if-symbol
+create-symbol lambda lambda-symbol
+create-symbol λ λ-symbol
\ }}}
objvar vals
: get-vars-vals-frame ( var frame -- bool )
- 2dup frame-vars vars setobj
- frame-vals vals setobj
+ 2dup frame-vars vars obj!
+ frame-vals vals obj!
begin
- vars fetchobj nil objeq? false =
+ vars obj@ nil objeq? false =
while
- 2dup vars fetchobj car objeq? if
+ 2dup vars obj@ car objeq? if
2drop true
exit
then
- vars fetchobj cdr vars setobj
- vals fetchobj cdr vals setobj
+ vars obj@ cdr vars obj!
+ vals obj@ cdr vals obj!
repeat
2drop false
2over 2over first-frame
get-vars-vals-frame if
2drop 2drop
- vars fetchobj vals fetchobj true
+ vars obj@ vals obj@ true
exit
then
objvar env
: define-var ( var val env -- )
- env setobj
+ env obj!
- 2over env fetchobj ( var val var env )
+ 2over env obj@ ( var val var env )
get-vars-vals if
2swap 2drop ( var val vals )
set-car!
2drop
else
- env fetchobj
+ env obj@
first-frame ( var val frame )
add-binding
then
objvar global-env
nil nil nil extend-env
-global-env setobj
+global-env obj!
+
+\ }}}
+
+\ ---- Primitives ---- {{{
+
+: make-primitive ( cfa -- )
+ bl word
+ count
+
+ \ 2dup ." Defining primitive " type ." ..." cr
+
+ (create-symbol)
+ drop symbol-type
+
+ 2dup
+
+ symbol-table obj@
+ cons
+ symbol-table obj!
+
+ rot primitive-proc-type ( var prim )
+ global-env obj@ define-var
+;
+
+: arg-count-error
+ bold fg red ." Incorrect argument count." reset-term cr
+ abort
+;
+
+: ensure-arg-count ( args n -- )
+ dup 0= if
+ drop nil objeq? false = if
+ arg-count-error
+ then
+ else
+ -rot 2dup nil objeq? if
+ arg-count-error
+ then
+
+ cdr rot 1- recurse
+ then
+;
+
+: arg-type-error
+ bold fg red ." Incorrect argument type." reset-term cr
+ abort
+;
+
+: ensure-arg-type ( arg type -- arg )
+ istype? false = if
+ arg-type-error
+ then
+;
+
+include scheme-primitives.4th
\ }}}
nextchar [char] ) = or
;
+: commentstart? ( -- bool )
+ nextchar [char] ; = ;
+
: eatspaces
+
+ false \ Indicates whether or not we're eating a comment
+
begin
- whitespace?
+ dup whitespace? or commentstart? or
while
+ dup nextchar '\n' = and if
+ invert \ Stop eating comment
+ else
+ dup false = commentstart? and if
+ invert \ Begin eating comment
+ then
+ then
+
inc-parse-idx
repeat
+ drop
;
: digit? ( -- bool )
: minus? ( -- bool )
nextchar [char] - = ;
-: number? ( -- bool )
- digit? minus? or false = if
- false
- exit
+: plus? ( -- bool )
+ nextchar [char] + = ;
+
+: fixnum? ( -- bool )
+ minus? plus? or if
+ inc-parse-idx
+
+ delim? if
+ dec-parse-idx
+ false exit
+ else
+ dec-parse-idx
+ then
+ else
+ digit? false = if
+ false exit
+ then
then
push-parse-idx
inc-parse-idx
repeat
- delim? if
- pop-parse-idx
- true
- else
- pop-parse-idx
- false
+ delim? pop-parse-idx
+;
+
+: realnum? ( -- bool )
+ push-parse-idx
+
+ minus? plus? or if
+ inc-parse-idx
+ then
+
+ \ Record starting parse idx:
+ \ Want to detect whether any characters (following +/-) were eaten.
+ parse-idx @
+
+ begin digit? while
+ inc-parse-idx
+ repeat
+
+ [char] . nextchar = if
+ inc-parse-idx
+ begin digit? while
+ inc-parse-idx
+ repeat
then
+
+ [char] e nextchar = [char] E nextchar = or if
+ inc-parse-idx
+
+ minus? plus? or if
+ inc-parse-idx
+ then
+
+ digit? invert if
+ drop pop-parse-idx false exit
+ then
+
+ begin digit? while
+ inc-parse-idx
+ repeat
+ then
+
+ \ This is a real number if characters were
+ \ eaten and the next characer is a delimiter.
+ parse-idx @ < delim? and
+
+ pop-parse-idx
;
: boolean? ( -- bool )
: string? ( -- bool )
nextchar [char] " = ;
-: readnum ( -- num-atom )
- minus? dup if
+: readfixnum ( -- num-atom )
+ plus? minus? or if
+ minus?
inc-parse-idx
+ else
+ false
then
0
swap if negate then
- number-type
+ fixnum-type
+;
+
+: readrealnum ( -- realnum )
+
+ \ Remember that at this point we're guaranteed to
+ \ have a parsable real on this line.
+
+ parse-str parse-idx @ +
+
+ begin delim? false = while
+ inc-parse-idx
+ repeat
+
+ parse-str parse-idx @ + over -
+
+ float-parse
+
+ realnum-type
;
: readbool ( -- bool-atom )
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 ( -- pairobj )
eatspaces
eatspaces
- number? if
- readnum
+ fixnum? if
+ readfixnum
+ exit
+ then
+
+ realnum? if
+ readrealnum
exit
then
then
eof? if
- bold fg blue ." Moriturus te saluto." reset-term ." ok" cr
+ inc-parse-idx
+ bold fg blue ." Moriturus te saluto." reset-term cr
quit
then
\ Anything else is parsed as a symbol
readsymbol charlist>symbol
+ \ Replace λ with lambda
+ 2dup λ-symbol objeq? if
+ 2drop lambda-symbol
+ then
+
+
; is read
\ }}}
\ ---- Eval ---- {{{
-defer eval
-
: self-evaluating? ( obj -- obj bool )
boolean-type istype? if true exit then
- number-type istype? if true exit then
+ fixnum-type istype? if true exit then
+ realnum-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
: definition? ( obj -- obj bool )
define-symbol tagged-list? ;
+: make-lambda ( params body -- lambda-exp )
+ lambda-symbol -2rot cons cons ;
+
: definition-var ( obj -- var )
- cdr car ;
+ cdr car
+ symbol-type istype? false = if car then
+;
: definition-val ( obj -- val )
- cdr cdr car ;
+ 2dup cdr car symbol-type istype? if
+ 2drop
+ cdr cdr car
+ else
+ cdr 2swap cdr cdr
+ make-lambda
+ then
+;
: assignment? ( obj -- obj bool )
set!-symbol tagged-list? ;
then
;
-: true? ( boolobj -- boolean )
+: true? ( boolobj -- bool )
false? invert ;
+: lambda? ( obj -- obj bool )
+ lambda-symbol tagged-list? ;
+
+: lambda-parameters ( obj -- params )
+ cdr car ;
+
+: lambda-body ( obj -- body )
+ cdr cdr ;
+
+: make-procedure ( params body env -- proc )
+ nil
+ cons cons cons
+ drop compound-proc-type
+;
+
+: application? ( obj -- obj bool)
+ pair-type istype? ;
+
+: operator ( obj -- operator )
+ car ;
+
+: operands ( obj -- operands )
+ cdr ;
+
+: nooperands? ( operands -- bool )
+ nil objeq? ;
+
+: first-operand ( operands -- operand )
+ car ;
+
+: rest-operands ( operands -- other-operands )
+ cdr ;
+
+: list-of-vals ( args env -- vals )
+ 2swap
+
+ 2dup nooperands? if
+ 2swap 2drop
+ else
+ 2over 2over first-operand 2swap eval
+ -2rot rest-operands 2swap recurse
+ cons
+ then
+;
+
+: procedure-params ( proc -- params )
+ drop pair-type car ;
+
+: procedure-body ( proc -- body )
+ drop pair-type cdr car ;
+
+: procedure-env ( proc -- body )
+ drop pair-type cdr cdr car ;
+
+: apply ( proc args )
+ 2swap dup case
+ primitive-proc-type of
+ drop execute
+ endof
+
+ compound-proc-type of
+ 2dup procedure-body ( args proc body )
+ -2rot 2dup procedure-params ( body args proc params )
+ -2rot procedure-env ( body params args procenv )
+
+ extend-env ( body env )
+
+ 2swap ( env body )
+
+ begin
+ 2dup cdr 2dup nil objeq? false =
+ while
+ -2rot car 2over ( nextbody env exp env )
+ eval
+ 2drop \ discard result
+ 2swap ( env nextbody )
+ repeat
+
+ 2drop ( env body )
+ car 2swap ( exp env )
+
+ R> drop ['] eval goto-deferred \ Tail call optimization
+ endof
+
+ bold fg red ." Object not applicable. Aboring." reset-term cr
+ abort
+ endcase
+;
+
:noname ( obj env -- result )
2swap
if-alternative
then
- 2swap ['] eval goto
+ 2swap
+ ['] eval goto-deferred
+ then
+
+ lambda? if
+ 2dup lambda-parameters
+ 2swap lambda-body
+ 2rot make-procedure
+ exit
+ then
+
+ application? if
+ 2over 2over
+ operator 2swap eval
+ -2rot
+ operands 2swap list-of-vals
+
+ apply
+ exit
then
bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
\ ---- Print ---- {{{
-: printnum ( numobj -- ) drop 0 .R ;
+: printfixnum ( fixnumobj -- ) drop 0 .R ;
+
+: printrealnum ( realnumobj -- ) drop float-print ;
: printbool ( numobj -- )
drop if
: printnil ( nilobj -- )
2drop ." ()" ;
-defer print
: printpair ( pairobj -- )
2dup
car print
." . " print
;
+: printprim ( primobj -- )
+ 2drop ." <primitive procedure>" ;
+
+: printcomp ( primobj -- )
+ 2drop ." <compound procedure>" ;
+
:noname ( obj -- )
- number-type istype? if printnum exit then
+ fixnum-type istype? if printfixnum exit then
+ realnum-type istype? if printrealnum 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
+ primitive-proc-type istype? if printprim exit then
+ compound-proc-type istype? if printcomp exit then
bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr
abort
\ }}}
+\ ---- DEBUGGING ---- {{{
+
+false value debug-mode
+
+:noname
+ debug-mode if
+ ." Object: " 2dup cr print cr
+ ." Pairlike: " pairlike? if
+ ." TRUE"
+ pairlike-marked? if
+ ." (Marked)"
+ else
+ ." (Unmarked)"
+ then
+ else
+ ." FALSE"
+ then
+ cr ." [paused]"
+ key drop cr
+ then
+; is gc-mark-trace
+
+: gc-mark-sweep
+ gc-unmark
+ symbol-table obj@ gc-mark-obj
+ global-env obj@ gc-mark-obj
+ gc-sweep
+;
+
+: gc-count-marked
+ 0
+ scheme-memsize 0 do
+ nextfrees i + @ 0= if 1+ then
+ loop
+;
+
+: gc-zero-unmarked
+ scheme-memsize 0 do
+ nextfrees i + @ 0<> if
+ 0 car-cells i + !
+ 0 cdr-cells i + !
+ then
+ loop
+;
+
+\ }}}
+
+
\ ---- REPL ----
: repl
cr ." Welcome to scheme.forth.jl!" cr
." Use Ctrl-D to exit." cr
+
empty-parse-str
begin
cr bold fg green ." > " reset-term
read
- global-env fetchobj eval
+
+ global-env obj@ eval
+
fg cyan ." ; " print reset-term
again
;
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff