X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=blobdiff_plain;f=src%2Fscheme.4th;h=ec97f09761c26f8603c14001277cd08b6f5e7dd8;hp=669665a2e80c7a0667a4ad3ec86a8f91774ac24d;hb=724ff46a1b082bef48b310a85d5a82037c2a914c;hpb=0dadd5f58d2c204c7f621ccd3c42f75a3fd790a8

diff --git a/src/scheme.4th b/src/scheme.4th
index 669665a..ec97f09 100644
--- a/src/scheme.4th
+++ b/src/scheme.4th
@@ -10,6 +10,7 @@ include float.4th
 include debugging.4th
 
 defer read
+defer expand
 defer eval
 defer print
 
@@ -51,33 +52,21 @@ variable nextexception
     1 nextexception +!
     does> @ ;
 
-make-exception recoverable-exception
-make-exception unrecoverable-exception
-
-: display-exception-msg ( addr count -- )
+: except-message:
     bold fg red
     ." Exception: "
-    type
-    reset-term ;
-
-: throw" immediate 
-    [compile] s"
-
-    ['] rot , ['] dup ,
+;
 
-    [compile] if
-        ['] -rot ,
-        ['] display-exception-msg ,
-    [compile] then
+make-exception recoverable-exception
+make-exception unrecoverable-exception
 
-    ['] throw ,
-;
+: throw reset-term throw ;
 
 \ }}}
 
 \ ---- List-structured memory ---- {{{
 
-10000 constant scheme-memsize
+20000 constant scheme-memsize
 
 create car-cells scheme-memsize allot
 create car-type-cells scheme-memsize allot
@@ -103,7 +92,7 @@ variable nextfree
     then
 
     nextfree @ scheme-memsize >= if
-        unrecoverable-exception throw s" Out of memory!"
+        except-message: ." Out of memory!" unrecoverable-exception throw
     then
 ;
 
@@ -273,8 +262,8 @@ 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 eof               eof-symbol
+create-symbol no-match          no-match-symbol
 
 \ Symbol to be bound to welcome message procedure by library
 create-symbol welcome           welcome-symbol
@@ -471,24 +460,30 @@ objvar vals
 hide vars
 hide vals
 
+objvar var
+
 : lookup-var ( var env -- val )
+    2over var obj!
     get-vars-vals if
         2swap 2drop car
     else
-        recoverable-exception throw" Tried to read unbound variable."
+        except-message: ." tried to read unbound variable '" var obj@ print ." '." recoverable-exception  throw
     then
 ;
 
 : set-var ( var val env -- )
     >R >R 2swap R> R> ( val var env )
+    2over var obj!
     get-vars-vals if
         2swap 2drop ( val vals )
         set-car!
     else
-        recoverable-exception throw" Tried to set unbound variable."
+        except-message: ." tried to set unbound variable '" var obj@ print ." '." recoverable-exception throw
     then
 ;
 
+hide var
+
 objvar env
 
 : define-var ( var val env -- )
@@ -536,11 +531,11 @@ global-env obj!
 : ensure-arg-count ( args n -- )
     dup 0= if
         drop nil objeq? false = if
-            recoverable-exception throw" Too many arguments for primitive procedure."
+            except-message: ." Too many arguments for primitive procedure." recoverable-exception throw
         then
     else
         -rot nil? if
-            recoverable-exception throw" Too few arguments for primitive procedure."
+            except-message: ." Too few arguments for primitive procedure." recoverable-exception  throw
         then
         
         cdr rot 1- recurse
@@ -550,17 +545,17 @@ global-env obj!
 : ensure-arg-type-and-count ( tn tn-1 ... t2 t1 args n -- )
     dup 0= if
         drop nil objeq? false = if
-            recoverable-exception throw" Too many arguments for primitive procedure."
+            except-message: ." Too many arguments for primitive procedure." recoverable-exception throw
         then
     else
         -rot nil? if
-            recoverable-exception throw" Too few arguments for primitive procedure."
+            except-message: ." Too few arguments for primitive procedure." recoverable-exception throw
         then
 
         2dup cdr 2swap car ( ... t1 n args' arg1 )
         2rot 1- swap 2swap rot ( ... args' n-1 arg1 t1 )
         istype? false = if
-            recoverable-exception throw" Incorrect type for primitive procedure."
+            except-message: ." Incorrect type for primitive procedure." recoverable-exception throw
         then
 
         2drop recurse
@@ -630,7 +625,7 @@ global-env obj!
 
 : ensure-arg-type ( arg type -- arg )
     istype? false = if
-        recoverable-exception throw" Incorrect argument type for primitive procedure."
+        except-message: ." Incorrect argument type for primitive procedure." recoverable-exception throw
     then
 ;
 
@@ -644,6 +639,12 @@ objvar macro-table
 ( Look up macro in macro table. Returns nil if
   no macro is found. )
 : lookup-macro ( name_symbol -- proc )
+
+    symbol-type istype? invert if
+        \ Early exit if argument is not a symbol
+        2drop nil exit
+    then
+    
     macro-table obj@
 
     begin
@@ -1321,12 +1322,12 @@ parse-idx-stack parse-idx-sp !
     cdr ( env args )
 
     nil? if
-        recoverable-exception throw" no arguments to unquote."
+        except-message: ." no arguments to unquote." recoverable-exception throw
     then
 
     2dup cdr
     nil? false = if
-        recoverable-exception throw" too many arguments to unquote."
+        except-message: ." too many arguments to unquote." recoverable-exception throw
     then
 
     2drop car 2swap eval
@@ -1384,12 +1385,12 @@ defer eval-quasiquote-item
     2swap cdr ( env args )
 
     nil? if
-        recoverable-exception throw" no arguments to quasiquote."
+        except-message: ." no arguments to quasiquote." recoverable-exception throw
     then
 
     2dup cdr ( env args args-cdr )
     nil? false = if
-        recoverable-exception throw" too many arguments to quasiquote."
+        except-message: ." too many arguments to quasiquote." recoverable-exception throw
     then
 
     2drop car ( env arg )
@@ -1403,34 +1404,21 @@ defer eval-quasiquote-item
 : definition? ( obj -- obj bool )
     define-symbol tagged-list? ;
 
-: make-lambda ( params body -- lambda-exp )
-    lambda-symbol -2rot cons cons ;
-
-( 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
+: definition-var ( obj -- var )
+    cdr car ;
 
-    2swap car
-;
+: definition-val ( obj -- val )
+    cdr cdr car ;
 
 : eval-definition ( obj env -- res )
-    2dup 2rot ( env env obj )
-    definition-var-val ( env env var val )
-    2rot eval  ( env var val )
+    2swap
+    2over 2over
+    definition-val 2swap
+    eval
 
-    2rot ( var val env )
+    2swap definition-var 2swap
+
+    2rot
     define-var
 
     ok-symbol
@@ -1524,12 +1512,6 @@ hide env
 : lambda-body ( obj -- body )
     cdr cdr ;
 
-: 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
@@ -1600,7 +1582,7 @@ hide env
 : flatten-proc-args ( argvals argnames -- argvals' argnames' )
     nil? if
         2over nil? false = if
-            recoverable-exception throw" Too many arguments for compound procedure."
+            except-message: ." Too many arguments for compound procedure." recoverable-exception throw
         else
             2drop
         then
@@ -1617,7 +1599,7 @@ hide env
 
     2over
     nil? if
-        recoverable-exception throw" Too few arguments for compound procedure."
+        except-message: ." Too few arguments for compound procedure." recoverable-exception throw
     else
         cdr
     then
@@ -1652,27 +1634,20 @@ hide env
                 R> drop ['] eval goto-deferred  \ Tail call optimization
             endof
 
-            recoverable-exception throw" Object not applicable."
+            except-message: ." object '" drop print ." ' not applicable." recoverable-exception throw
         endcase
 ;
 
-( Simply evaluates the given procedure with expbody as its argument. )
-: macro-expand ( proc expbody -- result )
-    2swap
-    2dup procedure-body ( expbody proc procbody )
-    -2rot 2dup procedure-params ( procbody expbody proc argnames )
-    -2rot procedure-env ( procbody argnames expbody procenv )
-    
-    -2rot 2swap
-    flatten-proc-args
-    2swap 2rot
-
-    extend-env eval-sequence eval
-;
-
 :noname ( obj env -- result )
     2swap
 
+    \ --- DEBUG ---
+    ( 
+      fg yellow ." Evaluating: " bold 2dup print reset-term
+      space fg green ." PS: " bold depth . reset-term
+      space fg blue  ." RS: " bold RSP@ RSP0 - . reset-term cr
+    )
+
     self-evaluating? if
         2swap 2drop
         exit
@@ -1731,45 +1706,171 @@ hide env
         exit
     then
 
-    begin? if
-        begin-actions 2swap
-        eval-sequence
-        ['] eval goto-deferred
-    then
-
     application? if
 
         2over 2over ( env exp env exp )
         operator ( env exp env opname )
 
-        2dup lookup-macro nil? false = if
-             \ Macro function evaluation
+        2swap eval ( env exp proc )
 
-            ( env exp env opname mproc )
-            2swap 2drop -2rot 2drop cdr ( env mproc body )
+        -2rot ( proc env exp )
+        operands 2swap ( proc operands env )
+        list-of-vals ( proc argvals )
 
-            macro-expand
+        apply
+        exit
+    then
 
-            2swap
-            ['] eval goto-deferred
-        else
-           \ Regular function application
+    except-message: ." tried to evaluate object with unknown type." recoverable-exception throw
+; is eval
 
-            2drop ( env exp env opname )
+\ }}}
 
-            2swap eval ( env exp proc )
+\ ---- Macro Expansion ---- {{{
 
-            -2rot ( proc env exp )
-            operands 2swap ( proc operands env )
-            list-of-vals ( proc argvals )
+( Simply evaluates the given procedure with expbody as its argument. )
+: macro-eval ( proc expbody -- result )
+    2swap
+    2dup procedure-body ( expbody proc procbody )
+    -2rot 2dup procedure-params ( procbody expbody proc argnames )
+    -2rot procedure-env ( procbody argnames expbody procenv )
+    
+    -2rot 2swap
+    flatten-proc-args
+    2swap 2rot
 
-            apply
-            exit
-        then
+    extend-env eval-sequence eval
+;
+
+: expand-macro ( exp -- result )
+    pair-type istype? invert if exit then
+    2dup car symbol-type istype? invert if 2drop exit then
+    
+    lookup-macro nil? if
+        2drop exit then
+
+    2over cdr macro-eval
+
+    2dup no-match-symbol objeq? if
+        2drop exit
+    else
+        2swap 2drop
     then
 
-    recoverable-exception throw" Tried to evaluate object with unknown type."
-; is eval
+    R> drop ['] expand goto-deferred
+;
+
+: expand-quasiquote-item ( exp -- result )
+    nil? if exit then
+
+    unquote? if
+        unquote-symbol 2swap cdr car expand nil cons cons
+        exit
+    then
+
+    unquote-splicing? if
+        unquote-splicing-symbol 2swap cdr car expand nil cons cons
+        exit
+    then
+    
+    pair-type istype? if
+        2dup car recurse
+        2swap cdr recurse
+        cons
+    then
+;
+
+: expand-quasiquote ( exp -- result )
+    quasiquote-symbol 2swap cdr
+
+    expand-quasiquote-item
+
+    cons ;
+
+: expand-definition ( exp -- result )
+    define-symbol 2swap
+
+    2dup definition-var
+    2swap definition-val expand
+    nil ( define var val' nil )
+
+    cons cons cons ;
+
+: expand-assignment ( exp -- result )
+    set!-symbol 2swap
+
+    2dup assignment-var
+    2swap assignment-val expand
+    nil ( define var val' nil )
+
+    cons cons cons ;
+
+: expand-list ( exp -- res )
+    nil? if exit then
+
+    2dup car expand
+    2swap cdr recurse
+
+    cons ;
+
+: macro-definition-nameparams
+    cdr car ;
+
+: expand-define-macro ( exp -- res )
+    define-macro-symbol 2swap
+    2dup macro-definition-nameparams
+    2swap macro-definition-body expand-list
+
+    cons cons ;
+
+: expand-lambda ( exp -- res )
+    lambda-symbol 2swap
+    2dup lambda-parameters
+    2swap lambda-body expand-list
+
+    cons cons ;
+
+: expand-if ( exp -- res )
+    if-symbol 2swap
+    
+    2dup if-predicate expand
+    2swap 2dup if-consequent expand
+    2swap if-alternative none? if
+        2drop nil
+    else
+        expand nil cons
+    then
+
+    cons cons cons ;
+
+: expand-application ( exp -- res )
+    2dup operator expand
+    2swap operands expand-list
+
+    cons ;
+
+:noname ( exp -- result )
+    expand-macro
+
+    self-evaluating? if exit then
+
+    quote? if exit then
+
+    quasiquote? if expand-quasiquote exit then
+
+    definition? if expand-definition exit then
+
+    assignment? if expand-assignment exit then
+
+    macro-definition? if expand-define-macro exit then
+
+    lambda? if expand-lambda exit then
+
+    if? if expand-if exit then
+
+    application? if expand-application exit then
+
+; is expand
 
 \ }}}
 
@@ -1867,7 +1968,7 @@ hide env
     none-type istype? if printnone exit then
     port-type istype? if printport exit then
 
-    recoverable-exception throw" Tried to print object with unknown type."
+    except-message: ." tried to print object with unknown type." recoverable-exception throw
 ; is print
 
 \ }}}
@@ -1955,7 +2056,7 @@ variable gc-stack-depth
 ;
 
 :noname
-    ." GC! "
+    \ ." GC! "
 
     gc-unmark
 
@@ -1997,6 +2098,8 @@ variable gc-stack-depth
 
         2swap 2drop ( port obj )
 
+        expand
+
         global-env obj@ eval ( port res )
     again
 ;
@@ -2025,6 +2128,8 @@ variable gc-stack-depth
         true exit
     then
 
+    expand
+
     global-env obj@ eval
 
     fg cyan ." ; " print reset-term
@@ -2033,7 +2138,6 @@ variable gc-stack-depth
 ;
 
 : repl
-
     empty-parse-str
 
     enable-gc