X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=src%2Fscheme.4th;h=425b3782633ace22eb693fbc4f70945dbeea6c7c;hb=70a8db797c242289782d563b0d8a0368d137e7ab;hp=bb65be27e77a60d5f537157c1c45ef426e39f401;hpb=ace5f5fbaf83906bb9f2b8293a6a366757eac615;p=scheme.forth.jl.git

diff --git a/src/scheme.4th b/src/scheme.4th
index bb65be2..425b378 100644
--- a/src/scheme.4th
+++ b/src/scheme.4th
@@ -3,6 +3,7 @@ scheme definitions
 
 include term-colours.4th
 include defer-is.4th
+include goto.4th
 include catch-throw.4th
 include integer.4th
 include float.4th
@@ -10,6 +11,8 @@ include float.4th
 include debugging.4th
 
 defer read
+defer expand
+defer analyze
 defer eval
 defer print
 
@@ -161,6 +164,10 @@ variable nextfree
     R> R>
 ;
 
+: 2pick ( an bn an-1 bn-1 ... a0 b0 n -- an bn an-1 bn-1 ... a0 b0 an bn )
+    2* 1+ dup
+    >R pick R> pick ;
+
 \ }}}
 
 \ ---- Pre-defined symbols ---- {{{
@@ -261,8 +268,8 @@ 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
@@ -1403,34 +1410,21 @@ 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 +1518,6 @@ 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
@@ -1656,20 +1644,6 @@ hide env
         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
 
@@ -1738,12 +1712,6 @@ hide env
         exit
     then
 
-    begin? if
-        begin-actions 2swap
-        eval-sequence
-        ['] eval goto-deferred
-    then
-
     application? if
 
         2over 2over ( env exp env exp )
@@ -1764,6 +1732,324 @@ hide env
 
 \ }}}
 
+\ ---- Analyze ----
+
+: evaluate-eproc ( env eproc --- res )
+    begin
+        nil? invert
+    while
+        2dup car
+        2swap cdr
+    repeat
+    
+    2drop \ get rid of null
+
+    \ Final element of eproc list is primitive procedure
+    drop \ dump type signifier
+    goto \ jump straight to primitive procedure (executor)
+;
+
+: self-evaluating-executor ( env exp -- exp )
+    2swap 2drop ;
+
+: analyze-self-evaluating ( exp --- eproc )
+    ['] self-evaluating-executor primitive-proc-type
+    nil cons cons
+;
+
+: quote-executor ( env exp -- exp )
+    2swap 2drop ;
+
+: analyze-quoted ( exp -- eproc )
+    quote-body
+
+    ['] quote-executor primitive-proc-type
+    nil cons cons
+;
+
+: variable-executor ( env var -- val )
+    2swap lookup-var ;
+
+: analyze-variable ( exp -- eproc )
+    ['] variable-executor primitive-proc-type
+    nil cons cons
+;
+
+: definition-executor ( env var val-eproc -- ok )
+     2rot 2dup 2rot ( var env env val-eproc )
+    evaluate-eproc 2swap ( var val env )
+    define-var
+    ok-symbol
+;
+
+: analyze-definition ( exp -- eproc )
+    2dup definition-var
+    2swap definition-val analyze
+
+    ['] definition-executor primitive-proc-type
+    nil cons cons cons
+;
+
+: assignment-executor ( env var val-eproc -- ok )
+    2rot 2dup 2rot ( var env env val-eproc )
+    evaluate-eproc 2swap ( var val env )
+    set-var
+    ok-symbol
+;
+
+: analyze-assignment ( exp -- eproc )
+    2dup assignment-var
+    2swap assignment-val analyze ( var val-eproc )
+
+    ['] assignment-executor primitive-proc-type
+    nil cons cons cons
+;
+
+: if-executor ( env pproc cproc aproc -- res )
+    2rot 3 2pick 2swap ( env cproc aproc env pproc )
+    evaluate-eproc
+    true? if
+        2drop evaluate-eproc
+    else
+        2swap 2drop evaluate-eproc
+    then
+;
+
+: analyze-if ( exp -- eproc )
+    2dup if-predicate analyze
+    2swap 2dup if-consequent analyze
+    2swap if-alternative analyze
+
+    ['] if-executor primitive-proc-type
+    nil cons cons cons cons
+;
+
+: sequential-executor ( env eproc1 eproc2 -- res )
+    2swap 2 2pick 2swap ( env eproc2 env eproc1 )
+    evaluate-eproc 2drop
+    evaluate-eproc
+;
+
+: analyze-sequence ( explist -- eproc )
+    nil? if
+        except-message: ." Tried to analyze empty expression sequence." recoverable-exception throw
+    then
+
+    2dup car analyze
+    2swap cdr
+    nil? if
+        2drop
+    else
+        recurse
+        ['] sequential-executor
+        nil cons cons
+    then
+;
+
+: lambda-executor ( env params bproc -- res )
+    2rot make-procedure
+    ( Although this is packaged up as a regular compound procedure,
+      the "body" element contains an _eproc_ to be evaluated in an
+      environment resulting from extending env with the parameter
+      bindings. )
+;
+
+: analyze-lambda ( exp -- eproc )
+    2dup lambda-parameters
+    2swap lambda-body analyze-sequence
+
+    ['] lambda-executor primitive-proc-type
+    nil cons cons cons
+;
+
+:noname ( exp --- eproc )
+
+    self-evaluating? if
+        analyze-self-evaluating
+        exit
+    then
+
+    quote? if
+        analyze-quoted
+        exit
+    then
+    
+    variable? if
+        analyze-variable
+        exit
+    then
+
+    definition? if
+        analyze-definition
+        exit
+    then
+
+    assignment? if
+        analyze-assignment
+        exit
+    then
+
+    if? if
+        analyze-if
+        exit
+    then
+
+    lambda? if
+        analyze-lambda
+        exit
+    then
+
+; is analyze
+
+
+\ ---- Macro Expansion ---- {{{
+
+( 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
+
+    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
+
+    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
+
+\ }}}
+
 \ ---- Print ---- {{{
 
 : printfixnum ( fixnum -- ) drop 0 .R ;
@@ -1988,6 +2274,8 @@ variable gc-stack-depth
 
         2swap 2drop ( port obj )
 
+        expand
+
         global-env obj@ eval ( port res )
     again
 ;
@@ -1998,7 +2286,7 @@ variable gc-stack-depth
 
     include scheme-primitives.4th
 
-\    s" scheme-library.scm" load 2drop
+    \ s" scheme-library.scm" load 2drop
     
 \ }}}
 
@@ -2016,6 +2304,8 @@ variable gc-stack-depth
         true exit
     then
 
+    expand
+
     global-env obj@ eval
 
     fg cyan ." ; " print reset-term