make-type symbol-type
make-type primitive-proc-type
make-type compound-proc-type
+make-type continuation-type
make-type port-type
: istype? ( obj type -- obj bool )
over = ;
make-exception recoverable-exception
make-exception unrecoverable-exception
-: throw reset-term throw ;
+: throw reset-term cr throw ;
\ }}}
nextfree !
nextfree @ scheme-memsize >= if
- collect-garbage
+ collect-garbage
then
nextfree @ scheme-memsize >= if
cdr-cells + !
;
+variable object-stack-base
+: init-object-stack-base
+ depth object-stack-base ! ;
+
: nil 0 nil-type ;
: nil? nil-type istype? ;
: make-frame ( vars vals -- frame )
cons ;
+: add-frame-to-env ( frame env -- env )
+ cons ;
+
: frame-vars ( frame -- vars )
car ;
;
: extend-env ( vars vals env -- env )
- >R >R
- make-frame
- R> R>
- cons
+ -2rot make-frame
+ 2swap add-frame-to-env
;
-objvar vars
-objvar vals
-
-: get-vars-vals-frame ( var frame -- bool )
- 2dup frame-vars vars obj!
- frame-vals vals obj!
+: get-vals-frame ( var frame -- vals | nil )
+ 2dup frame-vars
+ 2swap frame-vals ( var vars vals )
begin
- vars obj@ nil objeq? false =
+ nil? false =
while
- 2dup vars obj@ car objeq? if
- 2drop true
+
+ -2rot ( vals var vars )
+ 2over 2over car objeq? if
+ 2drop 2drop
exit
then
- vars obj@ cdr vars obj!
- vals obj@ cdr vals obj!
+ cdr 2rot cdr
repeat
- 2drop false
+ 2drop 2drop 2drop
+ nil
;
-: get-vars-vals ( var env -- vars? vals? bool )
+: get-vals ( var env -- vals | nil )
begin
nil? false =
while
2over 2over first-frame
- get-vars-vals-frame if
- 2drop 2drop
- vars obj@ vals obj@ true
+ get-vals-frame nil? false = if
+ 2swap 2drop 2swap 2drop
exit
then
+ 2drop
+
enclosing-env
repeat
- 2drop 2drop
- false
+ 2swap 2drop
;
-hide vars
-hide vals
-
-objvar var
-
+objvar var \ Used only for error messages
: lookup-var ( var env -- val )
2over var obj!
- get-vars-vals if
- 2swap 2drop car
- else
- except-message: ." tried to read unbound variable '" var obj@ print ." '." recoverable-exception throw
+
+ get-vals nil? if
+ except-message: ." tried to read unbound variable '" var obj@ print ." '."
+ recoverable-exception throw
then
+
+ car
;
: set-var ( var val env -- )
- >R >R 2swap R> R> ( val var env )
- 2over var obj!
- get-vars-vals if
- 2swap 2drop ( val vals )
- set-car!
+ 2rot 2dup var obj! ( val env var )
+ 2swap ( val var env )
+ get-vals nil? if
+ except-message: ." tried to set unbound variable '" var obj@ print ." '."
+ recoverable-exception throw
else
- except-message: ." tried to set unbound variable '" var obj@ print ." '." recoverable-exception throw
+ ( val vals )
+ set-car!
then
;
-
hide var
-objvar env
-
: define-var ( var val env -- )
- env obj!
+ first-frame ( var val frame )
+ 2rot 2swap 2over 2over ( val var frame var frame )
- 2over env obj@ ( var val var env )
- get-vars-vals if
- 2swap 2drop ( var val vals )
- set-car!
+ get-vals-frame nil? if
2drop
- else
- env obj@
- first-frame ( var val frame )
+ -2rot 2swap 2rot
add-binding
+ else
+ ( val var frame vals )
+ 2swap 2drop 2swap 2drop
+ set-car!
then
;
-hide env
-
: make-procedure ( params body env -- proc )
nil
cons cons cons
\ }}}
+\ ---- Continuations ---- {{{
+
+: cons-return-stack ( -- listobj )
+ rsp@ 1- rsp0 = if
+ nil exit
+ then
+
+ nil rsp@ 1- rsp0 do
+ i 1+ @ fixnum-type 2swap cons
+ loop
+
+ rsp@ 1- rsp0 - fixnum-type 2swap cons
+;
+
+: cons-param-stack ( -- listobj )
+ nil
+
+ depth 2- object-stack-base @ = if
+ exit
+ then
+
+ depth 2- object-stack-base @ do
+ PSP0 i + 1 + @
+ PSP0 i + 2 + @
+
+ 2swap cons
+ 2 +loop
+
+ depth 2- 2/ fixnum-type 2swap cons
+;
+
+: make-continuation ( -- continuation true-obj )
+ \ true-obj allows calling code to detect whether
+ \ it is being called immediately following make-continuation
+ \ or by a restore-continuation.
+
+ cons-param-stack
+ cons-return-stack
+ cons drop continuation-type
+
+ true boolean-type
+;
+
+: continuation->pstack-list
+ drop pair-type car ;
+
+: continuation->rstack-list
+ drop pair-type cdr ;
+
+: stack-list-len ( stack-list -- n )
+ car drop
+;
+
+: restore-param-stack ( continuation -- obj_stack )
+ continuation->pstack-list
+ 2dup >R >R
+
+ ( Allocate stack space first using psp!,
+ then copy objects from list. )
+
+ car drop 2*
+ object-stack-base @ psp0 + + psp!
+
+ R> R> 2dup cdr
+ 2swap
+ stack-list-len 1- 0 swap do
+
+ 2dup car
+ PSP0 object-stack-base @ + i 2* + 2 + !
+ PSP0 object-stack-base @ + i 2* + 1 + !
+ cdr
+
+ -1 +loop
+
+ 2drop
+;
+
+: restore-return-stack ( continuation -- )
+
+ continuation->rstack-list
+
+ 2dup cdr 2swap stack-list-len ( list n )
+
+ dup RSP0 + RSP! \ expand return stack to accommodate entries
+
+ ( list n )
+
+ 1- \ initial offset n-1
+ 0 \ final offset 0
+ swap
+ do
+ 2dup cdr 2swap car drop
+ RSP0 i 1+ + !
+ -1 +loop
+
+ 2drop
+;
+
+: restore-continuation-with-arg ( continuation obj -- )
+
+ >R >R \ Store obj on return stack
+
+ 2dup >R >R \ Store copy of continuation on return stack
+
+ restore-param-stack
+
+ R> R> \ Pop continuation from return stack
+
+ R> R> \ Pop obj from return stack
+
+ 2swap
+
+ false boolean-type \ Add flag signifying continuation restore
+
+ 2swap
+
+ restore-return-stack
+;
+
+\ }}}
+
\ ---- Primitives ---- {{{
: make-primitive ( cfa -- )
exit
then
+ nextchar [char] ) = if
+ inc-parse-idx
+ except-message: ." unmatched closing parenthesis." recoverable-exception throw
+ then
+
\ Anything else is parsed as a symbol
readsymbol charlist>symbol
\ }}}
-\ ---- Eval ---- {{{
+\ ---- Syntax ---- {{{
: self-evaluating? ( obj -- obj bool )
boolean-type istype? if true exit then
: quote-body ( quote-obj -- quote-body-obj )
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
- except-message: ." no arguments to unquote." recoverable-exception throw
- then
-
- 2dup cdr
- nil? false = if
- except-message: ." too many arguments to unquote." recoverable-exception throw
- 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
- except-message: ." no arguments to quasiquote." recoverable-exception throw
- then
-
- 2dup cdr ( env args args-cdr )
- nil? false = if
- except-message: ." too many arguments to quasiquote." recoverable-exception throw
- then
-
- 2drop car ( env arg )
-
- eval-quasiquote-item
-;
-
: variable? ( obj -- obj bool )
symbol-type istype? ;
: definition-val ( obj -- val )
cdr cdr car ;
-: eval-definition ( obj env -- res )
- 2swap
- 2over 2over
- definition-val 2swap
- eval
-
- 2swap definition-var 2swap
-
- 2rot
- define-var
-
- ok-symbol
-;
-
: assignment? ( obj -- obj bool )
set!-symbol tagged-list? ;
: assignment-val ( obj -- val )
cdr cdr car ;
-: eval-assignment ( obj env -- res )
- 2swap
- 2over 2over ( env obj env obj )
- assignment-val 2swap ( env obj valexp env )
- eval ( env obj val )
-
- 2swap assignment-var 2swap ( env var val )
-
- 2rot ( var val env )
- set-var
-
- ok-symbol
-;
-
: macro-definition? ( obj -- obj bool )
define-macro-symbol tagged-list? ;
: 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? ;
: lambda-body ( obj -- body )
cdr 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? ;
: 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 ;
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
-
- except-message: ." object '" drop print ." ' not applicable." recoverable-exception throw
- endcase
-;
-
-:noname ( obj env -- result )
- 2swap
-
- \ --- DEBUG ---
- (
- fg yellow ." Evaluating: " bold 2dup print reset-term
- space fg green ." PS: " bold depth . reset-term
- space fg blue ." RS: " bold RSP@ RSP0 - . reset-term cr
- )
-
- self-evaluating? if
- 2swap 2drop
- exit
- then
-
- quote? if
- quote-body
- 2swap 2drop
- exit
- then
-
- quasiquote? if
- 2swap eval-quasiquote
- exit
- then
-
- variable? if
- 2swap lookup-var
- exit
- then
-
- definition? if
- 2swap eval-definition
- exit
- then
-
- assignment? if
- 2swap eval-assignment
- exit
- then
-
- macro-definition? if
- 2swap eval-define-macro
- exit
- then
-
- if? if
- 2over 2over
- if-predicate
- 2swap eval
-
- true? if
- if-consequent
- else
- if-alternative
- then
-
- 2swap
- ['] eval goto-deferred
- then
-
- lambda? if
- 2dup lambda-parameters
- 2swap lambda-body
- 2rot make-procedure
- exit
- then
-
- application? if
-
- 2over 2over ( env exp env exp )
- operator ( 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
-
- except-message: ." tried to evaluate object with unknown type." recoverable-exception throw
-; is eval
-
\ }}}
-\ ---- Analyze ----
+\ ---- Analyze ---- {{{
: evaluate-eproc ( eproc env --- res )
\ Final element of eproc list is primitive procedure
drop \ dump type signifier
- .s cr \ DEBUG
-
goto \ jump straight to primitive procedure (executor)
;
nil cons cons cons
;
-: if-executor ( cproc aproc pproc env -- res )
- 2swap 2over ( cproc aproc env pproc env -- res )
- evaluate-eproc
-
- true? if
- 2swap 2drop
- else
- 2rot 2drop
- then
-
- evaluate-eproc
-;
-
-: analyze-if ( exp -- eproc )
- 2dup if-predicate analyze
- 2swap 2dup if-consequent analyze
- 2swap if-alternative analyze
-
- ['] if-executor primitive-proc-type
- nil cons cons cons cons
-;
-
: sequence-executor ( eproc-list env -- res )
2swap
2dup cdr ( env elist elist-rest)
nil? invert
while
-
-2rot car 2over ( elist-rest env elist-head env )
evaluate-eproc ( elist-rest env head-res )
2drop 2swap ( env elist-rest )
nil cons cons
;
+
+: macro-definition-executor ( name params bproc env -- ok )
+ make-macro ok-symbol
+;
+
+: analyze-macro-definition ( exp -- eproc )
+ 2dup macro-definition-name
+ 2swap 2dup macro-definition-params
+ 2swap macro-definition-body analyze-sequence
+
+ ['] macro-definition-executor primitive-proc-type
+ nil cons cons cons cons
+;
+
+: if-executor ( cproc aproc pproc env -- res )
+ 2swap 2over ( cproc aproc env pproc env -- res )
+ evaluate-eproc
+
+ true? if
+ 2swap 2drop
+ else
+ 2rot 2drop
+ then
+
+ ['] evaluate-eproc goto
+;
+
+: analyze-if ( exp -- eproc )
+ 2dup if-consequent analyze
+ 2swap 2dup if-alternative analyze
+ 2swap if-predicate analyze
+
+ ['] if-executor primitive-proc-type
+ nil cons cons cons cons
+;
+
: lambda-executor ( params bproc env -- res )
make-procedure
( Although this is packaged up as a regular compound procedure,
then
;
-: application-executor ( operator-proc arg-procs env -- res )
- 2rot 2over ( aprocs env fproc env )
- evaluate-eproc ( aprocs env proc )
-
- -2rot 2swap ( proc env aprocs )
- evaluate-operand-eprocs ( proc vals )
-
- 2swap ( vals proc )
-
+: apply ( vals proc )
dup case
primitive-proc-type of
drop execute
endof
compound-proc-type of
- 2dup procedure-body ( argvals proc body )
+ 2dup procedure-body ( argvals proc bproc )
-2rot 2dup procedure-params ( bproc argvals proc argnames )
-2rot procedure-env ( bproc argnames argvals procenv )
['] evaluate-eproc goto
endof
+ continuation-type of
+ 2swap
+ nil? if
+ except-message: ." Continuations expect exactly 1 argument."
+ recoverable-exception throw
+ then
+
+ 2dup cdr
+
+ nil? invert if
+ except-message: ." Continuations expect exactly 1 argument."
+ recoverable-exception throw
+ then
+
+ 2drop car
+
+ restore-continuation-with-arg
+ endof
+
except-message: ." object '" drop print ." ' not applicable." recoverable-exception throw
endcase
;
+: application-executor ( operator-proc arg-procs env -- res )
+ 2rot 2over ( aprocs env fproc env )
+ evaluate-eproc ( aprocs env proc )
+
+ -2rot 2swap ( proc env aprocs )
+ evaluate-operand-eprocs ( proc vals )
+
+ 2swap ( vals proc )
+
+ ['] apply goto
+;
+
: analyze-application ( exp -- eproc )
2dup operator analyze
2swap operands operand-eproc-list
:noname ( exp --- eproc )
- self-evaluating? if
- analyze-self-evaluating
- exit
- then
+ self-evaluating? if analyze-self-evaluating exit then
- quote? if
- analyze-quoted
- exit
- then
+ quote? if analyze-quoted exit then
- variable? if
- analyze-variable
- exit
- then
+ variable? if analyze-variable exit then
- definition? if
- analyze-definition
- exit
- then
+ definition? if analyze-definition exit then
- assignment? if
- analyze-assignment
- exit
- then
+ assignment? if analyze-assignment exit then
- if? if
- analyze-if
- exit
- then
+ macro-definition? if analyze-macro-definition exit then
- lambda? if
- analyze-lambda
- exit
- then
+ if? if analyze-if exit then
- application? if
- analyze-application
- exit
- then
+ lambda? if analyze-lambda exit then
+
+ application? if analyze-application exit then
-
except-message: ." tried to analyze unknown expression type." recoverable-exception throw
; is analyze
+\ }}}
\ ---- Macro Expansion ---- {{{
( Simply evaluates the given procedure with expbody as its argument. )
: macro-eval ( 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 )
+ 2dup procedure-body ( expbody proc bproc )
+ -2rot 2dup procedure-params ( bproc expbody proc argnames )
+ -2rot procedure-env ( bproc argnames expbody procenv )
-2rot 2swap
flatten-proc-args
2swap 2rot
- extend-env eval-sequence eval
+ extend-env ( bproc env )
+
+ ['] evaluate-eproc goto
;
: expand-macro ( exp -- result )
pair-type istype? invert if exit then
+
2dup car symbol-type istype? invert if 2drop exit then
-
- lookup-macro nil? if
- 2drop exit then
+
+ lookup-macro nil? if 2drop exit then
2over cdr macro-eval
R> drop ['] expand goto-deferred
;
-: expand-quasiquote-item ( exp -- result )
- nil? if exit then
-
- unquote? if
- unquote-symbol 2swap cdr car expand nil cons cons
- exit
- then
-
- unquote-splicing? if
- unquote-splicing-symbol 2swap cdr car expand nil cons cons
- exit
- then
-
- pair-type istype? if
- 2dup car recurse
- 2swap cdr recurse
- cons
- then
-;
-
-: expand-quasiquote ( exp -- result )
- quasiquote-symbol 2swap cdr
-
- expand-quasiquote-item
-
- cons ;
-
: expand-definition ( exp -- result )
define-symbol 2swap
quote? if exit then
- quasiquote? if expand-quasiquote exit then
-
definition? if expand-definition exit then
assignment? if expand-assignment exit then
\ }}}
+:noname ( exp env -- res )
+ 2swap expand analyze 2swap evaluate-eproc
+; is eval
+
\ ---- Print ---- {{{
: printfixnum ( fixnum -- ) drop 0 .R ;
: printcomp ( primobj -- )
2drop ." <compound procedure>" ;
+: printcont ( primobj --)
+ 2drop ." <continuation>" ;
+
: printnone ( noneobj -- )
2drop ." Unspecified return value" ;
pair-type istype? if ." (" printpair ." )" exit then
primitive-proc-type istype? if printprim exit then
compound-proc-type istype? if printcomp exit then
+ continuation-type istype? if printcont exit then
none-type istype? if printnone exit then
port-type istype? if printport exit then
\ ---- Garbage Collection ---- {{{
-variable gc-enabled
-false gc-enabled !
+( Notes on garbage collection:
+ This is a mark-sweep garbage collector, invoked by cons.
+ The roots of the object tree used by the marking routine
+ include all objects in the parameter stack, and several
+ other fixed roots such as global-env, symbol-table, macro-table,
+ and the console-i/o-port.
-variable gc-stack-depth
+ NO OTHER OBJECTS WILL BE MARKED!
-: enable-gc
- depth gc-stack-depth !
- true gc-enabled ! ;
+ This places implicit restrictions on when cons can be invoked.
+ Invoking cons when live objects are stored on the return stack
+ or in other variables than the above will result in possible
+ memory corruption if the cons triggers the GC. )
-: disable-gc
- false gc-enabled ! ;
-
-: gc-enabled?
- gc-enabled @ ;
: pairlike? ( obj -- obj bool )
pair-type istype? if true exit then
symbol-type istype? if true exit then
compound-proc-type istype? if true exit then
port-type istype? if true exit then
+ continuation-type istype? if true exit then
false
;
console-i/o-port obj@ gc-mark-obj
global-env obj@ gc-mark-obj
- depth gc-stack-depth @ do
+ depth object-stack-base @ do
PSP0 i + 1 + @
PSP0 i + 2 + @
ok-symbol ( port res )
begin
+ \ DEBUG
+ \ bold fg blue ." READ from " 2over drop . ." ==> " reset-term
+
2over read-port ( port res obj )
+ \ DEBUG
+ \ 2dup print cr
+
2dup EOF character-type objeq? if
2drop 2swap close-port
exit
2swap 2drop ( port obj )
- expand
-
global-env obj@ eval ( port res )
again
;
include scheme-primitives.4th
- \ s" scheme-library.scm" load 2drop
+ init-object-stack-base
+ s" scheme-library.scm" load 2drop
\ }}}
true exit
then
- expand
-
global-env obj@ eval
fg cyan ." ; " print reset-term
: repl
empty-parse-str
- enable-gc
+ init-object-stack-base
\ Display welcome message
- \ welcome-symbol nil cons global-env obj@ eval 2drop
+ welcome-symbol nil cons global-env obj@ eval 2drop
begin
['] repl-body catch
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff