include term-colours.4th
include defer-is.4th
+include catch-throw.4th
+include float.4th
-\ ------ Types ------
+include debugging.4th
-0 constant fixnum-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
-7 constant primitive-type
+defer read
+defer eval
+defer print
+
+defer collect-garbage
+
+\ ---- Types ---- {{{
+
+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 none-type
+make-type pair-type
+make-type symbol-type
+make-type primitive-proc-type
+make-type compound-proc-type
+make-type fileport-type
: istype? ( obj type -- obj bool )
over = ;
-\ ------ Cons cell memory ------ {{{
+\ }}}
+
+\ ---- Exceptions ---- {{{
+
+variable nextexception
+1 nextexception !
+: make-exception
+ create nextexception @ ,
+ 1 nextexception +!
+ does> @ ;
+
+make-exception recoverable-exception
+make-exception unrecoverable-exception
+
+: display-exception-msg ( addr count -- )
+ bold fg red
+ ." Exception: "
+ type
+ reset-term ;
+
+: throw" immediate
+ [compile] s"
+
+ ['] rot , ['] dup ,
+
+ [compile] if
+ ['] -rot ,
+ ['] display-exception-msg ,
+ [compile] then
+
+ ['] throw ,
+;
+
+\ }}}
+
+\ ---- List-structured memory ---- {{{
+
+10000 constant scheme-memsize
-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
+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 @ + @
+ nextfree !
+
+ nextfree @ scheme-memsize >= if
+ collect-garbage
+ then
+
+ nextfree @ scheme-memsize >= if
+ unrecoverable-exception throw s" Out of memory!"
+ 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 )
cdr-cells + !
;
-: caar car car ;
-: cadr cdr car ;
-: cdar car cdr ;
-: cddr cdr cdr ;
-
: nil 0 nil-type ;
: nil? nil-type istype? ;
+: none 0 none-type ;
+: none? none-type istype? ;
+
: objvar create nil swap , , ;
: 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+ @ ;
+: obj! ( newobj objvar -- ) dup rot swap 1+ ! ! ;
+: obj@ ( objvar -- obj ) dup @ swap 1+ @ ;
: objeq? ( obj obj -- bool )
rot = -rot = and ;
\ }}}
+\ ---- Port I/O ---- {{{
+
+: fileport>fid ( fileport -- fid )
+ drop ;
+
+: fid>fileport ( fid -- fileport )
+ fileport-type ;
+
+: open-input-file ( addr n -- fileport )
+ r/o open-file drop fid>fileport
+;
+
+: close-port ( fileport -- )
+ fileport>fid close-file drop
+;
+
+objvar console-i/o-port
+0 fileport-type console-i/o-port obj!
+
+objvar current-input-port
+console-i/o-port obj@ current-input-port obj!
+
+: read-port ( fileport -- obj )
+ current-input-port obj!
+ read ;
+
+: read-console ( -- obj )
+ console-i/o-port obj@ read-port ;
+
+\ }}}
+
\ ---- Pre-defined symbols ---- {{{
objvar symbol-table
-: (create-symbol) ( addr n -- symbol-obj )
+: duplicate-charlist ( charlist -- copy )
+ nil? 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!
+;
+
+
+: cstr>charlist ( addr n -- charlist )
dup 0= if
2drop nil
else
bl word
count
- (create-symbol)
- drop symbol-type
-
- 2dup
-
- symbol-table fetchobj
- cons
- symbol-table setobj
+ cstr>charlist
+ charlist>symbol
create swap , ,
does> dup @ swap 1+ @
;
-create-symbol quote quote-symbol
-create-symbol define define-symbol
-create-symbol set! set!-symbol
-create-symbol ok ok-symbol
-create-symbol if if-symbol
+create-symbol quote quote-symbol
+create-symbol quasiquote quasiquote-symbol
+create-symbol unquote unquote-symbol
+create-symbol unquote-splicing unquote-splicing-symbol
+create-symbol define define-symbol
+create-symbol define-macro define-macro-symbol
+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
+create-symbol begin begin-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
: get-vars-vals ( var env -- vars? vals? bool )
begin
- 2dup nil objeq? false =
+ nil? false =
while
2over 2over first-frame
get-vars-vals-frame if
2drop 2drop
- vars fetchobj vals fetchobj true
+ vars obj@ vals obj@ true
exit
then
get-vars-vals if
2swap 2drop car
else
- bold fg red ." Tried to read unbound variable." reset-term cr abort
+ recoverable-exception throw" Tried to read unbound variable."
then
;
2swap 2drop ( val vals )
set-car!
else
- bold fg red ." Tried to set unbound variable." reset-term cr abort
+ recoverable-exception throw" Tried to set unbound variable."
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
hide env
+: make-procedure ( params body env -- proc )
+ nil
+ cons cons cons
+ drop compound-proc-type
+;
+
objvar global-env
nil nil nil extend-env
-global-env setobj
+global-env obj!
\ }}}
bl word
count
- (create-symbol)
- drop symbol-type
-
- 2dup
-
- symbol-table fetchobj
- cons
- symbol-table setobj
-
- rot primitive-type ( var prim )
- global-env fetchobj define-var
-;
+ \ 2dup ." Defining primitive " type ." ..." cr
-: arg-count-error
- bold fg red ." Incorrect argument count." reset-term cr
- abort
+ cstr>charlist
+ charlist>symbol
+
+ rot primitive-proc-type ( var prim )
+ global-env obj@ define-var
;
: ensure-arg-count ( args n -- )
dup 0= if
drop nil objeq? false = if
- arg-count-error
+ recoverable-exception throw" Too many arguments for primitive procedure."
then
else
- -rot 2dup nil objeq? if
- arg-count-error
+ -rot nil? if
+ recoverable-exception throw" Too few arguments for primitive procedure."
then
cdr rot 1- recurse
abort
;
-: ensure-arg-type ( arg type -- )
+: ensure-arg-type ( arg type -- arg )
istype? false = if
- arg-type-error
+ recoverable-exception throw" Incorrect argument type for primitive procedure."
then
;
-include scheme-primitives.4th
\ }}}
-\ ---- Read ---- {{{
+\ ---- Macros ---- {{{
-defer read
+objvar macro-table
+
+( Look up macro in macro table. Returns nil if
+ no macro is found. )
+: lookup-macro ( name_symbol -- proc )
+ macro-table obj@
+
+ begin
+ nil? false =
+ while
+ 2over 2over
+ car car objeq? if
+ 2swap 2drop
+ car cdr
+ exit
+ then
+
+ cdr
+ repeat
+
+ 2swap 2drop
+;
+
+: make-macro ( name_symbol params body env -- )
+ make-procedure
+
+ 2swap ( proc name_symbol )
+
+ macro-table obj@
+
+ begin
+ nil? false =
+ while
+ 2over 2over ( proc name table name table )
+ car car objeq? if
+ 2swap 2drop ( proc table )
+ car ( proc entry )
+ set-cdr!
+ exit
+ then
+
+ cdr
+ repeat
+
+ 2drop
+
+ 2swap cons
+ macro-table obj@ cons
+ macro-table obj!
+;
+
+\ }}}
+
+\ ---- Read ---- {{{
variable parse-idx
variable stored-parse-idx
'\n' parse-str parse-str-span @ + !
1 parse-str-span +! ;
+: append-eof
+ 4 parse-str parse-str-span @ + !
+ 1 parse-str-span +! ;
+
: empty-parse-str
0 parse-str-span !
0 parse-idx ! ;
: getline
- parse-str 160 expect cr
- span @ parse-str-span !
+ current-input-port obj@ console-i/o-port obj@ objeq? if
+ parse-str 160 expect cr
+ span @ parse-str-span !
+ else
+ parse-str 160 current-input-port obj@ fileport>fid read-line
+ drop swap parse-str-span !
+
+ parse-str-span @ 0= and if append-eof then
+ then
append-newline
0 parse-idx ! ;
charavailable? false = if getline then
parse-str parse-idx @ + @ ;
+: '\t' 9 ;
: whitespace? ( -- bool )
nextchar BL =
- nextchar '\n' = or ;
+ nextchar '\n' =
+ nextchar '\t' =
+ or or ;
+: EOF 4 ;
: eof? ( -- bool )
- nextchar 4 = ;
+ nextchar EOF = ;
: delim? ( -- bool )
whitespace?
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] - = ;
+: plus? ( -- bool )
+ nextchar [char] + = ;
+
: fixnum? ( -- bool )
- minus? if
+ minus? plus? or if
inc-parse-idx
delim? if
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
fixnum-type
;
-: readbool ( -- bool-atom )
+: 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-obj )
inc-parse-idx
nextchar [char] f = if
boolean-type
;
-: readchar ( -- char-atom )
+: readchar ( -- char-obj )
inc-parse-idx
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
-;
-
: readpair ( -- pairobj )
eatspaces
eatspaces
fixnum? if
- readnum
+ readfixnum
+ exit
+ then
+
+ realnum? if
+ readrealnum
exit
then
quote-symbol recurse nil cons cons exit
then
- eof? if
- bold fg blue ." Moriturus te saluto." reset-term ." ok" cr
- quit
+ nextchar [char] ` = if
+ inc-parse-idx
+ quasiquote-symbol recurse nil cons cons exit
then
- \ Anything else is parsed as a symbol
- readsymbol charlist>symbol
-
-; is read
+ nextchar [char] , = if
+ inc-parse-idx
+ nextchar [char] @ = if
+ inc-parse-idx
+ unquote-splicing-symbol recurse nil cons cons exit
+ else
+ unquote-symbol recurse nil cons cons exit
+ then
+ then
+
+ eof? if
+ EOF character-type
+ inc-parse-idx
+ exit
+ 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
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
+ none-type istype? if true exit then
false
;
quote-symbol tagged-list? ;
: quote-body ( quote-obj -- quote-body-obj )
- cadr ;
+ cdr car ;
+
+: quasiquote? ( obj -- obj bool )
+ quasiquote-symbol tagged-list? ;
+
+: unquote? ( obj -- obj bool )
+ unquote-symbol tagged-list? ;
+
+: unquote-splicing? ( obj -- obj bool )
+ unquote-splicing-symbol tagged-list? ;
+
+: eval-unquote ( env obj -- res )
+ cdr ( env args )
+
+ nil? if
+ recoverable-exception throw" no arguments to unquote."
+ then
+
+ 2dup cdr
+ nil? false = if
+ recoverable-exception throw" too many arguments to unquote."
+ then
+
+ 2drop car 2swap eval
+;
+
+( Create a new list from elements of l1 consed on to l2 )
+: join-lists ( l2 l1 -- l3 )
+ nil? if 2drop exit then
+
+ 2dup car
+ -2rot cdr
+ recurse cons
+;
+
+defer eval-quasiquote-item
+: eval-quasiquote-pair ( env obj -- res )
+ 2over 2over ( env obj env obj )
+
+ cdr eval-quasiquote-item
+
+ -2rot car ( cdritem env objcar )
+
+ unquote-splicing? if
+ eval-unquote ( cdritems caritem )
+
+ 2swap nil? if
+ 2drop
+ else
+ 2swap join-lists
+ then
+ else
+ eval-quasiquote-item ( cdritems caritem )
+ 2swap cons
+ then
+
+;
+
+:noname ( env obj )
+ nil? if
+ 2swap 2drop exit
+ then
+
+ unquote? if
+ eval-unquote exit
+ then
+
+ pair-type istype? if
+ eval-quasiquote-pair exit
+ then
+
+ 2swap 2drop
+; is eval-quasiquote-item
+
+: eval-quasiquote ( obj env -- res )
+ 2swap cdr ( env args )
+
+ nil? if
+ recoverable-exception throw" no arguments to quasiquote."
+ then
+
+ 2dup cdr ( env args args-cdr )
+ nil? false = if
+ recoverable-exception throw" too many arguments to quasiquote."
+ then
+
+ 2drop car ( env arg )
+
+ eval-quasiquote-item
+;
: variable? ( obj -- obj bool )
symbol-type istype? ;
: definition? ( obj -- obj bool )
define-symbol tagged-list? ;
-: definition-var ( obj -- var )
- cdr car ;
+: make-lambda ( params body -- lambda-exp )
+ lambda-symbol -2rot cons cons ;
-: definition-val ( obj -- val )
- cdr cdr car ;
+( Handles iterative expansion of defines in
+ terms of nested lambdas. Most Schemes only
+ handle one iteration of expansion! )
+: definition-var-val ( obj -- var val )
-: assignment? ( obj -- obj bool )
- set!-symbol tagged-list? ;
+ cdr 2dup cdr 2swap car ( val var )
-: assignment-var ( obj -- var )
- cdr car ;
-
-: assignment-val ( obj -- val )
- cdr cdr car ;
+ begin
+ symbol-type istype? false =
+ while
+ 2dup cdr 2swap car ( val formals var' )
+ -2rot 2swap ( var' formals val )
+ make-lambda nil cons ( var' val' )
+ 2swap ( val' var' )
+ repeat
+
+ 2swap car
+;
: eval-definition ( obj env -- res )
- 2swap
- 2over 2over ( env obj env obj )
- definition-val 2swap ( env obj valexp env )
- eval ( env obj val )
-
- 2swap definition-var 2swap ( env var val )
+ 2dup 2rot ( env env obj )
+ definition-var-val ( env env var val )
+ 2rot eval ( env var val )
2rot ( var val env )
define-var
ok-symbol
;
+
+: assignment? ( obj -- obj bool )
+ set!-symbol tagged-list? ;
+
+: assignment-var ( obj -- var )
+ cdr car ;
+: assignment-val ( obj -- val )
+ cdr cdr car ;
+
: eval-assignment ( obj env -- res )
2swap
2over 2over ( env obj env obj )
ok-symbol
;
+: macro-definition? ( obj -- obj bool )
+ define-macro-symbol tagged-list? ;
+
+: macro-definition-name ( exp -- mname )
+ cdr car car ;
+
+: macro-definition-params ( exp -- params )
+ cdr car cdr ;
+
+: macro-definition-body ( exp -- body )
+ cdr cdr ;
+
+objvar env
+: eval-define-macro ( obj env -- res )
+ env obj!
+
+ 2dup macro-definition-name 2swap ( name obj )
+ 2dup macro-definition-params 2swap ( name params obj )
+ macro-definition-body ( name params body )
+
+ env obj@ ( name params body env )
+
+ make-macro
+
+ ok-symbol
+;
+hide env
+
: if? ( obj -- obj bool )
if-symbol tagged-list? ;
: if-consequent ( ifobj -- conseq )
cdr cdr car ;
-: if-alternative ( ifobj -- alt|false )
+: if-alternative ( ifobj -- alt|none )
cdr cdr cdr
- 2dup nil objeq? if
- 2drop false
+ nil? if
+ 2drop none
else
car
then ;
: true? ( boolobj -- bool )
false? invert ;
-: application? ( obj -- obj bool)
+: lambda? ( obj -- obj bool )
+ lambda-symbol tagged-list? ;
+
+: lambda-parameters ( obj -- params )
+ cdr car ;
+
+: lambda-body ( obj -- body )
+ cdr cdr ;
+
+: begin? ( obj -- obj bool )
+ begin-symbol tagged-list? ;
+
+: begin-actions ( obj -- actions )
+ cdr ;
+
+: eval-sequence ( explist env -- finalexp env )
+ ( Evaluates all bar the final expressions in
+ an an expression list. The final expression
+ is returned to allow for tail optimization. )
+
+ 2swap ( env explist )
+
+ \ Abort on empty list
+ nil? if
+ 2drop none
+ 2swap exit
+ then
+
+ begin
+ 2dup cdr ( env explist nextexplist )
+ nil? false =
+ while
+ -2rot car 2over ( nextexplist env exp env )
+ eval
+ 2drop \ discard result
+ 2swap ( env nextexplist )
+ repeat
+
+ 2drop car 2swap ( finalexp env )
+;
+
+: application? ( obj -- obj bool )
pair-type istype? ;
: operator ( obj -- operator )
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 ;
+
+( Ensure terminating symbol arg name is handled
+ specially to allow for variadic procedures. )
+: flatten-proc-args ( argvals argnames -- argvals' argnames' )
+ nil? if
+ 2over nil? false = if
+ recoverable-exception throw" Too many arguments for compound procedure."
+ else
+ 2drop
+ then
+ exit
+ then
+
+ symbol-type istype? if
+ nil cons
+ 2swap
+ nil cons
+ 2swap
+ exit
+ then
+
+ 2over
+ nil? if
+ recoverable-exception throw" Too few arguments for compound procedure."
+ else
+ cdr
+ then
+
+ 2over cdr
+
+ recurse ( argvals argnames argvals'' argnames'' )
+ 2rot car 2swap cons ( argvals argvals'' argnames' )
+ 2rot car 2rot cons ( argnames' argvals' )
+ 2swap
+;
+
+: apply ( proc argvals -- result )
+ 2swap dup case
+ primitive-proc-type of
+ drop execute
+ endof
+
+ compound-proc-type of
+ 2dup procedure-body ( argvals proc body )
+ -2rot 2dup procedure-params ( body argvals proc argnames )
+ -2rot procedure-env ( body argnames argvals procenv )
+
+ -2rot 2swap
+ flatten-proc-args
+ 2swap 2rot
+
+ extend-env ( body env )
+
+ eval-sequence
+
+ R> drop ['] eval goto-deferred \ Tail call optimization
+ endof
+
+ recoverable-exception throw" Object not applicable."
+ endcase
+;
+
+( Simply evaluates the given procedure with expbody as its argument. )
+: macro-expand ( proc expbody -- result )
+ 2swap
+ 2dup procedure-body ( expbody proc procbody )
+ -2rot 2dup procedure-params ( procbody expbody proc argnames )
+ -2rot procedure-env ( procbody argnames expbody procenv )
+
+ -2rot 2swap
+ flatten-proc-args
+ 2swap 2rot
+
+ extend-env eval-sequence eval
+;
+
:noname ( obj env -- result )
2swap
exit
then
+ quasiquote? if
+ 2swap eval-quasiquote
+ exit
+ then
+
variable? if
2swap lookup-var
exit
exit
then
+ macro-definition? if
+ 2swap eval-define-macro
+ exit
+ then
+
if? if
2over 2over
if-predicate
if-alternative
then
- 2swap ['] eval goto
+ 2swap
+ ['] eval goto-deferred
+ then
+
+ lambda? if
+ 2dup lambda-parameters
+ 2swap lambda-body
+ 2rot make-procedure
+ exit
+ then
+
+ begin? if
+ begin-actions 2swap
+ eval-sequence
+ ['] eval goto-deferred
then
application? if
- 2over 2over
- operator 2swap eval
- primitive-type istype? false = if
- bold fg red ." Object not applicable. Aboring." reset-term cr
- abort
- then
+ 2over 2over ( env exp env exp )
+ operator ( env exp env opname )
- -2rot
- operands 2swap list-of-vals
+ 2dup lookup-macro nil? false = if
+ \ Macro function evaluation
- 2swap drop execute
- exit
+ ( env exp env opname mproc )
+ 2swap 2drop -2rot 2drop cdr ( env mproc body )
+
+ macro-expand
+
+ 2swap
+ ['] eval goto-deferred
+ else
+ \ Regular function application
+
+ 2drop ( env exp env opname )
+
+ 2swap eval ( env exp proc )
+
+ -2rot ( proc env exp )
+ operands 2swap ( proc operands env )
+ list-of-vals ( proc argvals )
+
+ apply
+ exit
+ then
then
- bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
- abort
+ recoverable-exception throw" Tried to evaluate object with unknown type."
; is eval
\ }}}
\ ---- Print ---- {{{
-defer print
+: printfixnum ( fixnumobj -- ) drop 0 .R ;
-: printnum ( numobj -- ) drop 0 .R ;
+: printrealnum ( realnumobj -- ) drop float-print ;
: printbool ( numobj -- )
drop if
;
: (printstring) ( stringobj -- )
- nil-type istype? if 2drop exit then
+ nil? if 2drop exit then
2dup car drop dup
case
: printprim ( primobj -- )
2drop ." <primitive procedure>" ;
+: printcomp ( primobj -- )
+ 2drop ." <compound procedure>" ;
+
+: printnone ( noneobj -- )
+ 2drop ." Unspecified return value" ;
+
+: printport ( port -- )
+ 2drop ." <port>" ;
+
:noname ( obj -- )
- fixnum-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-type istype? if printprim exit then
+ primitive-proc-type istype? if printprim exit then
+ compound-proc-type istype? if printcomp exit then
+ none-type istype? if printnone exit then
- bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr
- abort
+ recoverable-exception throw" Tried to print object with unknown type."
; is print
\ }}}
+\ ---- Garbage Collection ---- {{{
+
+variable gc-enabled
+false gc-enabled !
+
+variable gc-stack-depth
+
+: enable-gc
+ depth gc-stack-depth !
+ true gc-enabled ! ;
+
+: disable-gc
+ 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
+;
+
+: gc-mark-obj ( obj -- )
+
+ 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
+;
+
+\ Following a GC, this gives the amount of free memory
+: gc-count-marked
+ 0
+ scheme-memsize 0 do
+ nextfrees i + @ 0= if 1+ then
+ loop
+;
+
+\ Debugging word - helps spot memory that is retained
+: gc-zero-unmarked
+ scheme-memsize 0 do
+ nextfrees i + @ 0<> if
+ 0 car-cells i + !
+ 0 cdr-cells i + !
+ then
+ loop
+;
+
+:noname
+ \ ." GC! "
+
+ gc-unmark
+
+ symbol-table obj@ gc-mark-obj
+ macro-table obj@ gc-mark-obj
+ global-env obj@ gc-mark-obj
+
+ depth gc-stack-depth @ do
+ PSP0 i + 1 + @
+ PSP0 i + 2 + @
+
+ gc-mark-obj
+ 2 +loop
+
+ gc-sweep
+
+ \ ." (" gc-count-marked . ." pairs marked as used.)" cr
+; is collect-garbage
+
+\ }}}
+
+\ ---- Loading files ---- {{{
+
+: charlist>cstr ( charlist addr -- n )
+
+ dup 2swap ( origaddr addr charlist )
+
+ begin
+ nil? false =
+ while
+ 2dup cdr 2swap car
+ drop ( origaddr addr charlist char )
+ -rot 2swap ( origaddr charlist addr char )
+ over !
+ 1+ -rot ( origaddr nextaddr charlist )
+ repeat
+
+ 2drop ( origaddr finaladdr )
+ swap -
+;
+
+: load ( addr n -- finalResult )
+ open-input-file
+
+ empty-parse-str
+
+ ok-symbol ( port res )
+
+ begin
+ 2over read-port ( port res obj )
+
+ 2dup EOF character-type objeq? if
+ 2drop 2swap close-port
+ exit
+ then
+
+ 2swap 2drop ( port obj )
+
+ global-env obj@ eval ( port res )
+ again
+;
+
+\ }}}
+
+\ ---- Standard Library ---- {{{
+
+ include scheme-primitives.4th
+
+ s" scheme-library.scm" load 2drop
+
+\ }}}
+
\ ---- REPL ----
+( REPL calls REPL-BODY in a loop until repl-body returns true. )
+: repl-body ( -- bool )
+ cr bold fg green ." > " reset-term
+
+ read-console
+
+ 2dup EOF character-type objeq? if
+ 2drop
+ bold fg blue ." Moriturus te saluto." reset-term cr
+ true exit
+ then
+
+ global-env obj@ eval
+
+ fg cyan ." ; " print reset-term
+
+ false
+;
+
: repl
cr ." Welcome to scheme.forth.jl!" cr
." Use Ctrl-D to exit." cr
empty-parse-str
+ enable-gc
+
begin
- cr bold fg green ." > " reset-term
- read
- global-env fetchobj eval
- fg cyan ." ; " print reset-term
- again
+ ['] repl-body catch
+ case
+ recoverable-exception of false endof
+ unrecoverable-exception of true endof
+
+ throw false
+ endcase
+ until
;
forth definitions
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff