4 constant nil-type
5 constant pair-type
6 constant symbol-type
+7 constant primitive-type
: istype? ( obj type -- obj bool )
over = ;
: objeq? ( obj obj -- bool )
rot = -rot = and ;
+: 2rot ( a1 a2 b1 b2 c1 c2 -- b1 b2 c1 c2 a1 a2 )
+ >R >R ( a1 a2 b1 b2 )
+ 2swap ( b1 b2 a1 a2 )
+ R> R> ( b1 b2 a1 a2 c1 c2 )
+ 2swap
+;
+
+: -2rot ( a1 a2 b1 b2 c1 c2 -- c1 c2 a1 a2 b1 b2 )
+ 2swap ( a1 a2 c1 c2 b1 b2 )
+ >R >R ( a1 a2 c1 c2 )
+ 2swap ( c1 c2 a1 a2 )
+ R> R>
+;
+
\ }}}
\ ---- Pre-defined symbols ---- {{{
does> dup @ swap 1+ @
;
-create-symbol quote quote-symbol
-create-symbol define define-symbol
-create-symbol set! set!-symbol
+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
\ }}}
\ ---- Environments ---- {{{
-objvar global-env
-
: enclosing-env ( env -- env )
cdr ;
: add-binding ( var val frame -- )
2swap 2over frame-vals cons
- 2over set-car!
+ 2over set-cdr!
2swap 2over frame-vars cons
- swap set-cdr!
+ 2swap set-car!
;
: extend-env ( vars vals env -- env )
2dup nil objeq? false =
while
2over 2over first-frame
- lookup-var-frame if
+ get-vars-vals-frame if
2drop 2drop
vars fetchobj vals fetchobj true
exit
get-vars-vals if
2swap 2drop car
else
- bold fg red ." Tried to read unbound variable." reset-term abort
+ bold fg red ." Tried to read unbound variable." reset-term cr abort
then
;
2swap 2drop ( val vals )
set-car!
else
- bold fg red ." Tried to set unbound variable." reset-term abort
+ bold fg red ." Tried to set unbound variable." reset-term cr abort
then
;
objvar env
: define-var ( var val env -- )
- env objset
+ env setobj
- 2over env objfetch ( var val var env )
+ 2over env fetchobj ( var val var env )
get-vars-vals if
2swap 2drop ( var val vals )
set-car!
2drop
else
- env objfetch
+ env fetchobj
first-frame ( var val frame )
add-binding
then
hide env
+objvar global-env
+nil nil nil extend-env
+global-env setobj
+
+\ }}}
+
+\ ---- Primitives ---- {{{
+
+: make-primitive ( cfa -- )
+ 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
+;
+
+: add-prim ( args -- )
+ nil objeq? if
+ 0 number-type
+ else
+ 2dup cdr recurse drop
+ -rot car drop
+ + number-type
+ then
+;
+
+' add-prim make-primitive +
+
\ }}}
\ ---- Read ---- {{{
+defer read
+
variable parse-idx
variable stored-parse-idx
create parse-str 161 allot
symbol-table setobj
;
-defer read
-
: readpair ( -- pairobj )
eatspaces
\ ---- Eval ---- {{{
+defer eval
+
: self-evaluating? ( obj -- obj bool )
boolean-type istype? if true exit then
number-type istype? if true exit then
: definition? ( obj -- obj bool )
define-symbol tagged-list? ;
+: definition-var ( obj -- var )
+ cdr car ;
+
+: definition-val ( obj -- val )
+ cdr cdr car ;
+
: assignment? ( obj -- obj bool )
- set-symbol tagged-list? ;
+ set!-symbol tagged-list? ;
+
+: assignment-var ( obj -- var )
+ cdr car ;
+
+: 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 )
-: eval ( obj env -- result )
+ 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 )
+ 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
+;
+
+: if? ( obj -- obj bool )
+ if-symbol tagged-list? ;
+
+: if-predicate ( ifobj -- pred )
+ cdr car ;
+
+: if-consequent ( ifobj -- conseq )
+ cdr cdr car ;
+
+: if-alternative ( ifobj -- alt|false )
+ cdr cdr cdr
+ 2dup nil objeq? if
+ 2drop false
+ else
+ car
+ then ;
+
+: false? ( boolobj -- boolean )
+ boolean-type istype? if
+ false boolean-type objeq?
+ else
+ 2drop false
+ then
+;
+
+: true? ( boolobj -- bool )
+ false? invert ;
+
+: applicaion? ( 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
+;
+
+:noname ( obj env -- result )
2swap
self-evaluating? if
exit
then
+ definition? if
+ 2swap eval-definition
+ exit
+ then
+
+ assignment? if
+ 2swap eval-assignment
+ exit
+ then
+
+ if? if
+ 2over 2over
+ if-predicate
+ 2swap eval
+
+ true? if
+ if-consequent
+ else
+ if-alternative
+ then
+
+ 2swap ['] eval goto
+ 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
+
+ -2rot
+ operands 2swap list-of-vals
+
+ 2swap drop execute
+ exit
+ then
+
bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
abort
-;
+; is eval
\ }}}
\ ---- Print ---- {{{
+defer print
+
: printnum ( numobj -- ) drop 0 .R ;
: printbool ( numobj -- )
: printnil ( nilobj -- )
2drop ." ()" ;
-defer print
: printpair ( pairobj -- )
2dup
car print
." . " print
;
+: printprim ( primobj -- )
+ 2drop ." <primitive procedure>" ;
+
:noname ( obj -- )
number-type istype? if printnum exit then
boolean-type istype? if printbool 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
bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr
abort
;
forth definitions
+
+\ vim:fdm=marker
The Lambda Lab / projects / scheme.forth.jl.git / blobdiff