X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=ae88b4b44d746e824a9cd0c4e6e29ae49e0a24d6;hb=659d7bdec81c23987b40c130008633e18f7001e7;hp=4dee70f16a352f0bf8f6ab483facb697a7db141d;hpb=b2a917e726a54a7cc3b21b8559cd166d3c2100f7;p=scheme.forth.jl.git

diff --git a/scheme.4th b/scheme.4th
index 4dee70f..ae88b4b 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -6,13 +6,14 @@ include defer-is.4th
 
 \ ------ Types ------
 
-0 constant number-type
+0 constant fixnum-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
+7 constant primitive-type
 : istype? ( obj type -- obj bool )
     over = ;
 
@@ -82,12 +83,86 @@ variable nextfree
 : 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 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
+;
+
+
 : (create-symbol) ( addr n -- symbol-obj )
     dup 0= if
         2drop nil
@@ -121,6 +196,7 @@ 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
 
 \ }}}
 
@@ -143,9 +219,9 @@ create-symbol ok        ok-symbol
 
 : 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 )
@@ -203,7 +279,7 @@ 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
 ;
 
@@ -213,7 +289,7 @@ 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
 ;
 
@@ -242,8 +318,63 @@ 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
+;
+
+: 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 ---- {{{
 
+defer read
+
 variable parse-idx
 variable stored-parse-idx
 create parse-str 161 allot
@@ -306,12 +437,27 @@ 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 )
@@ -322,10 +468,23 @@ 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
@@ -412,8 +571,11 @@ 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
@@ -425,7 +587,7 @@ parse-idx-stack parse-idx-sp !
 
     swap if negate then
 
-    number-type
+    fixnum-type
 ;
 
 : readbool ( -- bool-atom )
@@ -497,62 +659,6 @@ 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
 
@@ -600,7 +706,7 @@ defer read
 
     eatspaces
 
-    number? if
+    fixnum? if
         readnum
         exit
     then
@@ -656,6 +762,7 @@ defer read
     then
 
     eof? if
+        inc-parse-idx
         bold fg blue ." Moriturus te saluto." reset-term ."  ok" cr
         quit
     then
@@ -669,9 +776,11 @@ defer read
 
 \ ---- Eval ---- {{{
 
+defer eval
+
 : 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
@@ -714,8 +823,6 @@ defer read
 : assignment-val ( obj -- val )
     cdr cdr car ;
 
-defer eval
-
 : eval-definition ( obj env -- res )
     2swap 
     2over 2over ( env obj env obj )
@@ -724,7 +831,7 @@ defer eval
     
     2swap definition-var 2swap ( env var val )
 
-    >R >R 2swap R> R> 2swap ( var val env )
+    2rot ( var val env )
     define-var
 
     ok-symbol
@@ -738,12 +845,70 @@ defer eval
     
     2swap assignment-var 2swap ( env var val )
 
-    >R >R 2swap R> R> 2swap ( var val env )
+    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 ;
+
+: 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
+;
+
 :noname ( obj env -- result )
     2swap
 
@@ -773,6 +938,36 @@ defer eval
         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
@@ -781,6 +976,8 @@ defer eval
 
 \ ---- Print ---- {{{
 
+defer print
+
 : printnum ( numobj -- ) drop 0 .R ;
 
 : printbool ( numobj -- )
@@ -830,7 +1027,6 @@ defer eval
 : printnil ( nilobj -- )
     2drop ." ()" ;
 
-defer print
 : printpair ( pairobj -- )
     2dup
     car print
@@ -840,14 +1036,18 @@ defer print
     ."  . " print
 ;
 
+: printprim ( primobj -- )
+    2drop ." <primitive 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-type istype? if printprim exit then
 
     bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr
     abort
@@ -872,3 +1072,5 @@ defer print
 ;
 
 forth definitions
+
+\ vim:fdm=marker