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-warning ( addr count -- )
+ bold fg red
+ ." Exception: "
+ type
+ reset-term ;
+
+: throw" immediate
+ [compile] s"
+
+ ['] rot , ['] dup ,
+
+ [compile] if
+ ['] -rot ,
+ ['] display-warning ,
+ [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
;
;
-: cstr>charlist ( addr n -- symbol-obj )
+: cstr>charlist ( addr n -- charlist )
dup 0= if
2drop nil
else
count
cstr>charlist
- drop symbol-type
-
- 2dup
-
- symbol-table obj@
- cons
- symbol-table obj!
+ charlist>symbol
create swap , ,
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 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
: 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 )
( 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' )
: apply ( proc argvals -- result )
2swap dup case
primitive-proc-type of
- drop execute
+ drop execute
endof
compound-proc-type of
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
;
application? if
2over 2over ( env exp env exp )
- operator 2dup ( env exp env opname opname )
+ operator ( env exp env opname )
+
+ 2dup lookup-macro nil? false = if
+ \ Macro function evaluation
+
+ ( env exp env opname mproc )
+ 2swap 2drop -2rot 2drop cdr ( env mproc body )
- lookup-macro nil? if
- \ Regular function application
+ 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
- else
- \ 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
+ exit
then
- exit
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
\ }}}
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 ---- {{{
-
-: make-primitive ( cfa -- )
- bl word
- count
+\ ---- Standard Library ---- {{{
- \ 2dup ." Defining primitive " type ." ..." cr
+ include scheme-primitives.4th
- cstr>charlist
- drop symbol-type
+ s" scheme-library.scm" load 2drop
- 2dup
-
- symbol-table obj@
- cons
- symbol-table obj!
+\ }}}
- 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
-;
-
-: arg-type-error
- bold fg red ." Incorrect argument type." reset-term cr
- abort
-;
+ read-console
-: 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
+ global-env obj@ eval
-\ }}}
-
-\ ---- Standard Library ---- {{{
+ fg cyan ." ; " print reset-term
- s" scheme-library.scm" load 2drop
-
-\ }}}
-
-\ ---- REPL ----
+ false
+;
: repl
cr ." Welcome to scheme.forth.jl!" cr
enable-gc
begin
- cr bold fg green ." > " reset-term
- read-console
+ ['] repl-body catch
+ case
+ recoverable-exception of false endof
+ unrecoverable-exception of true endof
- 2dup EOF character-type objeq? if
- 2drop
- bold fg blue ." Moriturus te saluto." reset-term cr
- exit
- then
-
- global-env obj@ eval
+ \ Rethrow anything else:
+ throw
- fg cyan ." ; " print reset-term
- again
+ \ If we're still here, loop again
+ false
+ endcase
+ until
;
forth definitions
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff