X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=e1126ff0868bcc7a6bca3bdbefc1889d13a34ad1;hb=7c4b983db5c13783ed581b302becb7e8419123dc;hp=ee180fce679fdb07e26d8f45fec77744e0a5059d;hpb=817c66d1c66e6a02f9998b644fc963e72796e615;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index ee180fc..e1126ff 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -3,22 +3,37 @@ scheme definitions
 
 include term-colours.4th
 include defer-is.4th
+include throw-catch.4th
+
+defer read
+defer eval
+defer print
 
 \ ------ Types ------
 
-0 constant number-type
-1 constant boolean-type
-2 constant character-type
-3 constant string-type
-4 constant nil-type
-5 constant pair-type
-6 constant symbol-type
+variable nexttype
+0 nexttype !
+: make-type
+    create nexttype @ ,
+    nexttype @ 1+ nexttype !
+    does> @ ;
+
+make-type fixnum-type
+make-type real-type
+make-type boolean-type
+make-type character-type
+make-type string-type
+make-type nil-type
+make-type pair-type
+make-type symbol-type
+make-type primitive-proc-type
+make-type compound-proc-type
 : istype? ( obj type -- obj bool )
     over = ;
 
 \ ------ Cons cell memory ------ {{{
 
-1000 constant N
+10000 constant N
 create car-cells N allot
 create car-type-cells N allot
 create cdr-cells N allot
@@ -76,18 +91,92 @@ variable nextfree
 : type@ ( objvar -- type ) 1+ @ ;
 : value! ( newval objvar -- ) ! ;
 : type! ( newtype objvar -- ) 1+ ! ;
-: setobj ( newobj objvar -- ) dup rot swap 1+ ! ! ; 
-: fetchobj ( objvar -- obj ) dup @ swap 1+ @ ; 
+: obj! ( newobj objvar -- ) dup rot swap 1+ ! ! ; 
+: obj@ ( objvar -- obj ) dup @ swap 1+ @ ; 
 
 : 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 ---- {{{
 
 objvar symbol-table
 
+: duplicate-charlist ( charlist -- copy )
+    2dup nil objeq? false = if
+        2dup car 2swap cdr recurse cons
+    then ;
+
+: charlist-equiv ( charlist charlist -- bool )
+
+    2over 2over
+
+    \ One or both nil
+    nil? -rot 2drop
+    if
+        nil? -rot 2drop
+        if
+            2drop 2drop true exit
+        else
+            2drop 2drop false exit
+        then
+    else
+        nil? -rot 2drop
+        if
+            2drop 2drop false exit
+        then
+    then
+
+    2over 2over
+
+    \ Neither nil
+    car drop -rot car drop = if
+            cdr 2swap cdr recurse
+        else
+            2drop 2drop false
+    then
+;
+
+: charlist>symbol ( charlist -- symbol-obj )
+
+    symbol-table obj@
+
+    begin
+        nil? false =
+    while
+        2over 2over
+        car drop pair-type
+        charlist-equiv if
+            2swap 2drop
+            car
+            exit
+        else
+            cdr
+        then
+    repeat
+
+    2drop
+    drop symbol-type 2dup
+    symbol-table obj@ cons
+    symbol-table obj!
+;
+
+
 : (create-symbol) ( addr n -- symbol-obj )
     dup 0= if
         2drop nil
@@ -109,24 +198,26 @@ objvar symbol-table
 
     2dup
 
-    symbol-table fetchobj
+    symbol-table obj@
     cons
-    symbol-table setobj
+    symbol-table obj!
 
     create swap , ,
     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
+create-symbol lambda    lambda-symbol
+create-symbol λ         λ-symbol
 
 \ }}}
 
 \ ---- Environments ---- {{{
 
-objvar global-env
-
 : enclosing-env ( env -- env )
     cdr ;
 
@@ -144,9 +235,9 @@ objvar global-env
 
 : 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 )
@@ -160,19 +251,19 @@ objvar vars
 objvar vals
 
 : get-vars-vals-frame ( var frame -- bool )
-    2dup frame-vars vars setobj
-    frame-vals vals setobj
+    2dup frame-vars vars obj!
+    frame-vals vals obj!
 
     begin
-        vars fetchobj nil objeq? false =
+        vars obj@ nil objeq? false =
     while
-        2dup vars fetchobj car objeq? if
+        2dup vars obj@ car objeq? if
             2drop true
             exit
         then
 
-        vars fetchobj cdr vars setobj
-        vals fetchobj cdr vals setobj
+        vars obj@ cdr vars obj!
+        vals obj@ cdr vals obj!
     repeat
 
     2drop false
@@ -184,9 +275,9 @@ objvar vals
         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
+            vars obj@ vals obj@ true
             exit
         then
 
@@ -204,7 +295,7 @@ hide vals
     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
 ;
 
@@ -214,22 +305,22 @@ hide vals
         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 obj! 
 
-    2over env objfetch ( var val var env )
+    2over env obj@ ( var val var env )
     get-vars-vals if
         2swap 2drop ( var val vals )
         set-car!
         2drop
     else
-        env objfetch
+        env obj@
         first-frame ( var val frame )
         add-binding
     then
@@ -237,6 +328,63 @@ objvar env
 
 hide env
 
+objvar global-env
+nil nil nil extend-env
+global-env obj!
+
+\ }}}
+
+\ ---- Primitives ---- {{{
+
+: make-primitive ( cfa -- )
+    bl word
+    count
+
+    (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 ---- {{{
@@ -303,12 +451,27 @@ parse-idx-stack parse-idx-sp !
     nextchar [char] ) = or
 ;
 
+: commentstart? ( -- bool )
+    nextchar [char] ; = ;
+
 : eatspaces
+
+    false \ Indicates whether or not we're eating a comment
+
     begin
-        whitespace?
+        dup whitespace? or commentstart? or
     while
+        dup nextchar '\n' = and if
+            invert \ Stop eating comment
+        else
+            dup false = commentstart? and if   
+                invert \ Begin eating comment
+            then
+        then
+
         inc-parse-idx
     repeat
+    drop
 ;
 
 : digit? ( -- bool )
@@ -319,10 +482,23 @@ parse-idx-stack parse-idx-sp !
 : minus? ( -- bool )
     nextchar [char] - = ;
 
-: number? ( -- bool )
-    digit? minus? or false = if
-        false
-        exit
+: plus? ( -- bool )
+    nextchar [char] + = ;
+
+: fixnum? ( -- bool )
+    minus? plus? or if
+        inc-parse-idx
+
+        delim? if
+            dec-parse-idx
+            false exit
+        else
+            dec-parse-idx
+        then
+    else
+        digit? false = if
+            false exit
+        then
     then
 
     push-parse-idx
@@ -409,8 +585,11 @@ parse-idx-stack parse-idx-sp !
     nextchar [char] " = ;
 
 : readnum ( -- num-atom )
-    minus? dup if
+    plus? minus? or if
+        minus?
         inc-parse-idx
+    else
+        false
     then
 
     0
@@ -422,7 +601,7 @@ parse-idx-stack parse-idx-sp !
 
     swap if negate then
 
-    number-type
+    fixnum-type
 ;
 
 : readbool ( -- bool-atom )
@@ -494,62 +673,6 @@ parse-idx-stack parse-idx-sp !
     cons
 ;
 
-: charlist-equiv ( charlist charlist -- bool )
-
-    2over 2over
-
-    \ One or both nil
-    nil? -rot 2drop
-    if
-        nil? -rot 2drop
-        if
-            2drop 2drop true exit
-        else
-            2drop 2drop false exit
-        then
-    else
-        nil? -rot 2drop
-        if
-            2drop 2drop false exit
-        then
-    then
-
-    2over 2over
-
-    \ Neither nil
-    car drop -rot car drop = if
-            cdr 2swap cdr recurse
-        else
-            2drop 2drop false
-    then
-;
-
-: charlist>symbol ( charlist -- symbol-obj )
-
-    symbol-table fetchobj
-
-    begin
-        nil? false =
-    while
-        2over 2over
-        car drop pair-type
-        charlist-equiv if
-            2swap 2drop
-            car
-            exit
-        else
-            cdr
-        then
-    repeat
-
-    2drop
-    drop symbol-type 2dup
-    symbol-table fetchobj cons
-    symbol-table setobj
-;
-
-defer read
-
 : readpair ( -- pairobj )
     eatspaces
 
@@ -597,7 +720,7 @@ defer read
 
     eatspaces
 
-    number? if
+    fixnum? if
         readnum
         exit
     then
@@ -653,6 +776,7 @@ defer read
     then
 
     eof? if
+        inc-parse-idx
         bold fg blue ." Moriturus te saluto." reset-term ."  ok" cr
         quit
     then
@@ -660,6 +784,12 @@ defer read
     \ Anything else is parsed as a symbol
     readsymbol charlist>symbol
 
+    \ Replace λ with lambda
+    2dup λ-symbol objeq? if
+        2drop lambda-symbol
+    then
+    
+
 ; is read
 
 \ }}}
@@ -668,7 +798,7 @@ defer read
 
 : self-evaluating? ( obj -- obj bool )
     boolean-type istype? if true exit then
-    number-type istype? if true exit then
+    fixnum-type istype? if true exit then
     character-type istype? if true exit then
     string-type istype? if true exit then
     nil-type istype? if true exit then
@@ -696,10 +826,179 @@ defer read
 : definition? ( obj -- obj bool )
     define-symbol tagged-list? ;
 
+: make-lambda ( params body -- lambda-exp )
+    lambda-symbol -2rot cons cons ;
+
+: definition-var ( obj -- var )
+    cdr car
+    symbol-type istype? false = if car then
+;
+
+: definition-val ( obj -- val )
+    2dup cdr car symbol-type istype? if
+        2drop
+        cdr cdr car
+    else
+        cdr 2swap cdr cdr
+        make-lambda
+    then
+;
+
 : 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 ;
+
+: lambda? ( obj -- obj bool )
+    lambda-symbol tagged-list? ;
+
+: lambda-parameters ( obj -- params )
+    cdr car ;
+
+: lambda-body ( obj -- body )
+    cdr cdr ;
+
+: make-procedure ( params body env -- proc )
+    nil
+    cons cons cons
+    drop compound-proc-type
+;
+
+: application? ( 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
+;
+
+: procedure-params ( proc -- params )
+    drop pair-type car ;
+
+: procedure-body ( proc -- body )
+    drop pair-type cdr car ;
+
+: procedure-env ( proc -- body )
+    drop pair-type cdr cdr car ;
+
+: apply ( proc args )
+        2swap dup case
+            primitive-proc-type of
+                drop execute
+            endof
+
+            compound-proc-type of
+                2dup procedure-body ( args proc body )
+                -2rot 2dup procedure-params ( body args proc params )
+                -2rot procedure-env ( body params args procenv )
+
+                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 )
+
+                R> drop ['] eval goto-deferred  \ Tail call optimization
+            endof
+
+            bold fg red ." Object not applicable. Aboring." reset-term cr
+            abort
+        endcase
+;
+
+:noname ( obj env -- result )
     2swap
 
     self-evaluating? if
@@ -718,9 +1017,51 @@ defer read
         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-deferred
+    then
+
+    lambda? if
+        2dup lambda-parameters
+        2swap lambda-body
+        2rot make-procedure
+        exit
+    then
+
+    application? if
+        2over 2over
+        operator 2swap eval
+        -2rot
+        operands 2swap list-of-vals
+
+        apply
+        exit
+    then
+
     bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr
     abort
-;
+; is eval
 
 \ }}}
 
@@ -775,7 +1116,6 @@ defer read
 : printnil ( nilobj -- )
     2drop ." ()" ;
 
-defer print
 : printpair ( pairobj -- )
     2dup
     car print
@@ -785,14 +1125,22 @@ defer print
     ."  . " print
 ;
 
+: printprim ( primobj -- )
+    2drop ." <primitive procedure>" ;
+
+: printcomp ( primobj -- )
+    2drop ." <compound procedure>" ;
+
 :noname ( obj -- )
-    number-type istype? if printnum exit then
+    fixnum-type istype? if printnum exit then
     boolean-type istype? if printbool exit then
     character-type istype? if printchar exit then
     string-type istype? if printstring exit then
     symbol-type istype? if printsymbol exit then
     nil-type istype? if printnil exit then
     pair-type istype? if ." (" printpair ." )" exit then
+    primitive-proc-type istype? if printprim exit then
+    compound-proc-type istype? if printcomp exit then
 
     bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr
     abort
@@ -811,9 +1159,11 @@ defer print
     begin
         cr bold fg green ." > " reset-term
         read
-        global-env fetchobj eval
+        global-env obj@ eval
         fg cyan ." ; " print reset-term
     again
 ;
 
 forth definitions
+
+\ vim:fdm=marker