include term-colours.4th
include defer-is.4th
+include catch-throw.4th
include float.4th
include debugging.4th
defer collect-garbage
-\ ------ Types ------
+\ ---- Types ---- {{{
variable nexttype
0 nexttype !
: istype? ( obj type -- obj bool )
over = ;
+\ }}}
+
+\ ---- 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
then
nextfree @ scheme-memsize >= if
- fg red bold
- ." Out of memory! Aborting."
- reset-term abort
+ unrecoverable-exception throw s" Out of memory!"
then
;
cdr-cells + !
;
-: caar car car ;
-: cadr cdr car ;
-: cdar car cdr ;
-: cddr cdr cdr ;
-
: nil 0 nil-type ;
: nil? nil-type istype? ;
does> dup @ swap 1+ @
;
-create-symbol quote quote-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
-create-symbol apply apply-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
\ }}}
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
;
nil nil nil extend-env
global-env obj!
+\ }}}
+
+\ ---- Primitives ---- {{{
+
+: make-primitive ( cfa -- )
+ bl word
+ count
+
+ \ 2dup ." Defining primitive " type ." ..." cr
+
+ 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
+ recoverable-exception throw" Too many arguments for primitive procedure."
+ then
+ else
+ -rot nil? if
+ recoverable-exception throw" Too few arguments for primitive procedure."
+ 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
+ recoverable-exception throw" Incorrect argument type for primitive procedure."
+ then
+;
+
+
\ }}}
\ ---- Macros ---- {{{
quote-symbol recurse nil cons cons exit
then
+ nextchar [char] ` = if
+ inc-parse-idx
+ quasiquote-symbol recurse nil cons cons exit
+ then
+
+ 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
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? ;
: make-lambda ( params body -- lambda-exp )
lambda-symbol -2rot cons cons ;
-: definition-var ( obj -- var )
- cdr car
- symbol-type istype? false = if car then
+( Handles iterative expansion of defines in
+ terms of nested lambdas. Most Schemes only
+ handle one iteration of expansion! )
+: definition-var-val ( obj -- var val )
+
+ cdr 2dup cdr 2swap car ( val var )
+
+ 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
;
-: definition-val ( obj -- val )
- 2dup cdr car symbol-type istype? if
- 2drop
- cdr cdr car
- else
- cdr 2swap cdr cdr
- make-lambda
- then
+: eval-definition ( obj env -- res )
+ 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 )
: assignment-val ( obj -- val )
cdr cdr 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 )
-
- 2rot ( var val env )
- define-var
-
- ok-symbol
-;
-
: eval-assignment ( obj env -- res )
2swap
2over 2over ( env obj env obj )
: if-consequent ( ifobj -- conseq )
cdr cdr car ;
-: if-alternative ( ifobj -- alt|false )
+: if-alternative ( ifobj -- alt|none )
cdr cdr cdr
nil? if
- 2drop false
+ 2drop none
else
car
then ;
( Ensure terminating symbol arg name is handled
specially to allow for variadic procedures. )
: flatten-proc-args ( argvals argnames -- argvals' argnames' )
- nil? if exit then
+ 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
exit
then
- 2over cdr 2over cdr
+ 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' )
R> drop ['] eval goto-deferred \ Tail call optimization
endof
- bold fg red ." Object not applicable. Aborting." reset-term cr
- abort
+ 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 )
exit
then
+ quasiquote? if
+ 2swap eval-quasiquote
+ exit
+ then
+
variable? if
2swap lookup-var
exit
2over 2over ( env exp env exp )
operator ( env exp env opname )
- 2dup apply-symbol objeq? if
-
- 2drop 2swap ( env env exp )
- cdr 2dup car 2rot ( env expbody real-opname env )
- eval ( env expbody proc )
- 2swap cdr
- nil? false = if car then ( env proc real-operand )
-
- 2rot eval ( proc argvals )
-
- pair-type istype? false = if
- bold fg red ." Error: apply requires a list of operand arguments." cr
- reset-term abort
- then
-
- apply
- exit
- then
-
2dup lookup-macro nil? false = if
\ Macro function evaluation
( env exp env opname mproc )
2swap 2drop -2rot 2drop cdr ( env mproc body )
- 2dup print cr
macro-expand
- 2dup print cr
2swap
['] eval goto-deferred
- then
+ else
+ \ Regular function application
- \ Regular function application
+ 2drop ( env exp env opname )
- 2drop ( env exp env opname )
+ 2swap eval ( env exp proc )
- 2swap eval ( env exp proc )
- -2rot ( proc env exp )
- operands 2swap ( proc operands env )
- list-of-vals ( proc argvals )
+ -2rot ( proc env exp )
+ operands 2swap ( proc operands env )
+ list-of-vals ( proc argvals )
- apply
- exit
+ 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
\ }}}
;
: (printstring) ( stringobj -- )
- nil-type istype? if 2drop exit then
+ nil? if 2drop exit then
2dup car drop dup
case
: printnone ( noneobj -- )
2drop ." Unspecified return value" ;
+: printport ( port -- )
+ 2drop ." <port>" ;
+
:noname ( obj -- )
fixnum-type istype? if printfixnum exit then
realnum-type istype? if printrealnum 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
\ }}}
\ }}}
-\ ---- Primitives ---- {{{
+\ ---- Standard Library ---- {{{
-: make-primitive ( cfa -- )
- bl word
- count
+ include scheme-primitives.4th
- \ 2dup ." Defining primitive " type ." ..." cr
+ s" scheme-library.scm" load 2drop
+
+\ }}}
- cstr>charlist
- charlist>symbol
-
- rot primitive-proc-type ( var prim )
- global-env obj@ define-var
-;
+\ ---- REPL ----
-: arg-count-error
- bold fg red ." Incorrect argument count." reset-term cr
- abort
-;
+( REPL calls REPL-BODY in a loop until repl-body returns true. )
+: repl-body ( -- bool )
+ cr bold fg green ." > " reset-term
-: ensure-arg-count ( args n -- )
- dup 0= if
- drop nil objeq? false = if
- arg-count-error
- then
- else
- -rot nil? if
- arg-count-error
- then
-
- cdr rot 1- recurse
- then
-;
+ read-console
-: 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
+ 2dup EOF character-type objeq? if
+ 2drop
+ bold fg blue ." Moriturus te saluto." reset-term cr
+ true exit
then
-;
-
-include scheme-primitives.4th
-\ }}}
-
-\ ---- Standard Library ---- {{{
+ global-env obj@ eval
- s" scheme-library.scm" load 2drop
-
-\ }}}
+ fg cyan ." ; " print reset-term
-\ ---- REPL ----
+ false
+;
: repl
cr ." Welcome to scheme.forth.jl!" cr
enable-gc
begin
- cr bold fg green ." > " reset-term
- read-console
-
- 2dup EOF character-type objeq? if
- 2drop
- bold fg blue ." Moriturus te saluto." reset-term cr
- exit
- then
+ ['] repl-body catch
+ case
+ recoverable-exception of false endof
+ unrecoverable-exception of true endof
- global-env obj@ eval
-
- fg cyan ." ; " print reset-term
- again
+ throw false
+ endcase
+ until
;
forth definitions
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff