X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=136c8a85b3abec94c7ef9a86f5a04de4d1f0ff3d;hb=77eccf994da4cc6b875bcfe479d069153dd8158c;hp=3ea9d66e0598c0513ecc2595c0c202b8e3085a0f;hpb=c1614af3cb919d99081fb11d7ba2c1a83cb2d408;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index 3ea9d66..136c8a8 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -11,6 +11,8 @@ defer read
 defer eval
 defer print
 
+defer collect-garbage
+
 \ ------ Types ------
 
 variable nexttype
@@ -26,24 +28,27 @@ 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 ------ {{{
+\ ------ List-structured memory ------ {{{
+
+10000 constant scheme-memsize
 
-10000 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 N allot
+create nextfrees scheme-memsize allot
 :noname
-    N 0 do
+    scheme-memsize 0 do
         i 1+ nextfrees i + !
     loop
 ; execute
@@ -53,7 +58,18 @@ variable nextfree
 
 : inc-nextfree
     nextfrees nextfree @ + @
-    nextfree ! ;
+    nextfree !
+
+    nextfree @ scheme-memsize >= if
+        collect-garbage
+    then
+
+    nextfree @ scheme-memsize >= if
+        fg red bold
+        ." Out of memory! Aborting."
+        reset-term abort
+    then
+;
 
 : cons ( car-obj cdr-obj -- pair-obj )
     cdr-type-cells nextfree @ + !
@@ -97,6 +113,9 @@ variable nextfree
 : nil 0 nil-type ;
 : nil? nil-type istype? ;
 
+: none 0 none-type ;
+: none? none-type istype? ;
+
 : objvar create nil swap , , ;
 
 : value@ ( objvar -- val ) @ ;
@@ -125,61 +144,34 @@ variable nextfree
 
 \ }}}
 
-\ ---- Garbage Collection ---- {{{
-
-variable gc-enabled
-false gc-enabled !
-
-: gc-enable
-    true gc-enabled ! ;
-
-: gc-disable
-    false gc-enabled ! ;
-
-: gc-enabled?
-    gc-enabled @ ;
+\ ---- Port I/O ----  {{{
 
-: 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
+: fileport>fid ( fileport -- fid )
+    drop ;
 
-    false
-;
+: fid>fileport ( fid -- fileport )
+    fileport-type ;
 
-: pairlike-marked? ( obj -- obj bool )
-    over nextfrees + 0=
+: open-input-file ( addr n -- fileport )
+    r/o open-file drop fid>fileport
 ;
 
-: mark-pairlike ( obj -- obj )
-        over nextfrees + 0 swap !
+: close-port ( fileport -- )
+    fileport>fid close-file drop
 ;
 
-: gc-mark-obj ( obj -- )
-
-    pairlike? if
-        pairlike-marked? if 2drop exit then
-            
-        mark-pairlike
+objvar console-i/o-port
+0 fileport-type console-i/o-port obj!
 
-        2dup
+objvar current-input-port
+console-i/o-port obj@ current-input-port obj!
 
-        car recurse
-        cdr recurse
-    else
-        2drop
-    then
-;
+: read-port ( fileport -- obj )
+    current-input-port obj!
+    read ;
 
-: gc-sweep
-    N nextfree !
-    0 N 1- do
-        nextfrees i + @ 0<> if
-            nextfree @ nextfrees i + !
-            i nextfree !
-        then
-    -1 +loop ;
+: read-console ( -- obj )
+    console-i/o-port obj@ read-port ;
 
 \ }}}
 
@@ -247,7 +239,7 @@ objvar symbol-table
 ;
 
 
-: (create-symbol) ( addr n -- symbol-obj )
+: cstr>charlist ( addr n -- symbol-obj )
     dup 0= if
         2drop nil
     else
@@ -263,7 +255,7 @@ objvar symbol-table
     bl word
     count
 
-    (create-symbol)
+    cstr>charlist
     drop symbol-type
 
     2dup
@@ -283,6 +275,7 @@ 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
 
 \ }}}
 
@@ -404,61 +397,6 @@ global-env obj!
 
 \ }}}
 
-\ ---- Primitives ---- {{{
-
-: make-primitive ( cfa -- )
-    bl word
-    count
-
-    \ 2dup ." Defining primitive " type ." ..." cr
-
-    (create-symbol)
-    drop symbol-type
-    
-    2dup
-
-    symbol-table obj@
-    cons
-    symbol-table obj!
-
-    rot primitive-proc-type ( var prim )
-    global-env obj@ define-var
-;
-
-: arg-count-error
-            bold fg red ." Incorrect argument count." reset-term cr
-            abort
-;
-
-: ensure-arg-count ( args n -- )
-    dup 0= if
-        drop nil objeq? false = if
-            arg-count-error
-        then
-    else
-        -rot 2dup nil objeq? if
-            arg-count-error
-        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
-        arg-type-error
-    then
-;
-
-include scheme-primitives.4th
-
-\ }}}
-
 \ ---- Read ---- {{{
 
 variable parse-idx
@@ -487,13 +425,24 @@ parse-idx-stack parse-idx-sp !
     '\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 ! ;
 
@@ -510,12 +459,16 @@ parse-idx-stack parse-idx-sp !
     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?
@@ -733,7 +686,7 @@ parse-idx-stack parse-idx-sp !
     realnum-type
 ;
 
-: readbool ( -- bool-atom )
+: readbool ( -- bool-obj )
     inc-parse-idx
     
     nextchar [char] f = if
@@ -747,7 +700,7 @@ parse-idx-stack parse-idx-sp !
     boolean-type
 ;
 
-: readchar ( -- char-atom )
+: readchar ( -- char-obj )
     inc-parse-idx
     inc-parse-idx
 
@@ -910,9 +863,9 @@ parse-idx-stack parse-idx-sp !
     then
 
     eof? if
+        EOF character-type
         inc-parse-idx
-        bold fg blue ." Moriturus te saluto." reset-term cr
-        quit
+        exit
     then
 
     \ Anything else is parsed as a symbol
@@ -937,6 +890,7 @@ parse-idx-stack parse-idx-sp !
     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
 ;
@@ -1059,6 +1013,38 @@ parse-idx-stack parse-idx-sp !
     drop compound-proc-type
 ;
 
+: 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
+    2dup nil objeq? if
+        2drop none
+        2swap exit
+    then
+
+    begin
+        2dup cdr ( env explist nextexplist )
+        2dup nil objeq? 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? ;
 
@@ -1111,19 +1097,7 @@ parse-idx-stack parse-idx-sp !
 
                 extend-env ( body env )
 
-                2swap ( env body )
-
-                begin
-                    2dup cdr 2dup nil objeq? false =
-                while
-                    -2rot car 2over ( nextbody env exp env )
-                    eval
-                    2drop \ discard result
-                    2swap ( env nextbody )
-                repeat
-
-                2drop ( env body )
-                car 2swap ( exp env )
+                eval-sequence
 
                 R> drop ['] eval goto-deferred  \ Tail call optimization
             endof
@@ -1184,6 +1158,12 @@ parse-idx-stack parse-idx-sp !
         exit
     then
 
+    begin? if
+        begin-actions 2swap
+        eval-sequence
+        ['] eval goto-deferred
+    then
+
     application? if
         2over 2over
         operator 2swap eval
@@ -1268,6 +1248,9 @@ parse-idx-stack parse-idx-sp !
 : printcomp ( primobj -- )
     2drop ." <compound procedure>" ;
 
+: printnone ( noneobj -- )
+    2drop ." Unspecified return value" ;
+
 :noname ( obj -- )
     fixnum-type istype? if printfixnum exit then
     realnum-type istype? if printrealnum exit then
@@ -1279,6 +1262,7 @@ parse-idx-stack parse-idx-sp !
     pair-type istype? if ." (" printpair ." )" 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
@@ -1286,18 +1270,235 @@ parse-idx-stack parse-idx-sp !
 
 \ }}}
 
+\ ---- 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
+    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
+
+\ }}}
+
+\ ---- Primitives ---- {{{
+
+: make-primitive ( cfa -- )
+    bl word
+    count
+
+    \ 2dup ." Defining primitive " type ." ..." cr
+
+    cstr>charlist
+    drop symbol-type
+    
+    2dup
+
+    symbol-table obj@
+    cons
+    symbol-table obj!
+
+    rot primitive-proc-type ( var prim )
+    global-env obj@ define-var
+;
+
+: arg-count-error
+            bold fg red ." Incorrect argument count." reset-term cr
+            abort
+;
+
+: ensure-arg-count ( args n -- )
+    dup 0= if
+        drop nil objeq? false = if
+            arg-count-error
+        then
+    else
+        -rot 2dup nil objeq? if
+            arg-count-error
+        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
+        arg-type-error
+    then
+;
+
+include scheme-primitives.4th
+
+\ }}}
+
+\ ---- Loading files ---- {{{
+
+: charlist>cstr ( charlist addr -- n )
+
+    dup 2swap ( origaddr addr charlist )
+
+    begin 
+        2dup nil objeq? 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
+;
+
+:noname ( args -- finalResult )
+    2dup 1 ensure-arg-count
+    car string-type ensure-arg-type
+
+    drop pair-type
+    pad charlist>cstr
+    pad swap load
+; make-primitive load
+
+\ }}}
+
 \ ---- REPL ----
 
 : 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
+        read-console
+
+        2dup EOF character-type objeq? if
+            2drop
+            bold fg blue ." Moriturus te saluto." reset-term cr
+            exit
+        then
 
         global-env obj@ eval