X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=1796ea19631ff2bbad3907e675a53c2a722b5f9c;hb=7b36afd3962b8ac1389496d86da661664e03e20b;hp=c69f0ecbf67570f1c8400c4802dc186cae4b992d;hpb=21606409845e717c4760793e95326c25e4e95029;p=scheme.forth.jl.git diff --git a/scheme.4th b/scheme.4th index c69f0ec..1796ea1 100644 --- a/scheme.4th +++ b/scheme.4th @@ -3,32 +3,72 @@ scheme definitions include term-colours.4th include defer-is.4th +include float.4th + +include debugging.4th + +defer read +defer eval +defer print + +defer collect-garbage \ ------ Types ------ -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-proc-type -8 constant compound-proc-type +variable nexttype +0 nexttype ! +: make-type + create nexttype @ , + 1 nexttype +! + does> @ ; + +make-type fixnum-type +make-type realnum-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 ------ {{{ +\ ------ List-structured memory ------ {{{ + +10000 constant scheme-memsize -1000 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 scheme-memsize allot +:noname + scheme-memsize 0 do + i 1+ nextfrees i + ! + loop +; execute + variable nextfree 0 nextfree ! +: inc-nextfree + nextfrees 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 @ + ! cdr-cells nextfree @ + ! @@ -36,8 +76,7 @@ variable nextfree car-cells nextfree @ + ! nextfree @ pair-type - - 1 nextfree +! + inc-nextfree ; : car ( pair-obj -- car-obj ) @@ -78,8 +117,8 @@ 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 ; @@ -100,6 +139,7 @@ variable nextfree \ }}} + \ ---- Pre-defined symbols ---- {{{ objvar symbol-table @@ -141,7 +181,7 @@ objvar symbol-table : charlist>symbol ( charlist -- symbol-obj ) - symbol-table fetchobj + symbol-table obj@ begin nil? false = @@ -159,8 +199,8 @@ objvar symbol-table 2drop drop symbol-type 2dup - symbol-table fetchobj cons - symbol-table setobj + symbol-table obj@ cons + symbol-table obj! ; @@ -185,9 +225,9 @@ objvar symbol-table 2dup - symbol-table fetchobj + symbol-table obj@ cons - symbol-table setobj + symbol-table obj! create swap , , does> dup @ swap 1+ @ @@ -199,6 +239,7 @@ 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 \ }}} @@ -237,19 +278,19 @@ 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 @@ -263,7 +304,7 @@ objvar vals 2over 2over first-frame get-vars-vals-frame if 2drop 2drop - vars fetchobj vals fetchobj true + vars obj@ vals obj@ true exit then @@ -298,15 +339,15 @@ hide vals objvar env : define-var ( var val env -- ) - env setobj + env obj! - 2over env fetchobj ( 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 fetchobj + env obj@ first-frame ( var val frame ) add-binding then @@ -316,7 +357,7 @@ hide env objvar global-env nil nil nil extend-env -global-env setobj +global-env obj! \ }}} @@ -326,17 +367,19 @@ global-env setobj bl word count + \ 2dup ." Defining primitive " type ." ..." cr + (create-symbol) drop symbol-type 2dup - symbol-table fetchobj + symbol-table obj@ cons - symbol-table setobj + symbol-table obj! rot primitive-proc-type ( var prim ) - global-env fetchobj define-var + global-env obj@ define-var ; : arg-count-error @@ -375,8 +418,6 @@ include scheme-primitives.4th \ ---- Read ---- {{{ -defer read - variable parse-idx variable stored-parse-idx create parse-str 161 allot @@ -496,13 +537,52 @@ parse-idx-stack parse-idx-sp ! inc-parse-idx repeat - delim? if - pop-parse-idx - true - else - pop-parse-idx - false + delim? pop-parse-idx +; + +: realnum? ( -- bool ) + push-parse-idx + + minus? plus? or if + inc-parse-idx + then + + \ Record starting parse idx: + \ Want to detect whether any characters (following +/-) were eaten. + parse-idx @ + + begin digit? while + inc-parse-idx + repeat + + [char] . nextchar = if + inc-parse-idx + begin digit? while + inc-parse-idx + repeat + then + + [char] e nextchar = [char] E nextchar = or if + inc-parse-idx + + minus? plus? or if + inc-parse-idx + then + + digit? invert if + drop pop-parse-idx false exit + then + + begin digit? while + inc-parse-idx + repeat then + + \ This is a real number if characters were + \ eaten and the next characer is a delimiter. + parse-idx @ < delim? and + + pop-parse-idx ; : boolean? ( -- bool ) @@ -572,7 +652,7 @@ parse-idx-stack parse-idx-sp ! : string? ( -- bool ) nextchar [char] " = ; -: readnum ( -- num-atom ) +: readfixnum ( -- num-atom ) plus? minus? or if minus? inc-parse-idx @@ -592,7 +672,25 @@ parse-idx-stack parse-idx-sp ! fixnum-type ; -: readbool ( -- bool-atom ) +: readrealnum ( -- realnum ) + + \ Remember that at this point we're guaranteed to + \ have a parsable real on this line. + + parse-str parse-idx @ + + + begin delim? false = while + inc-parse-idx + repeat + + parse-str parse-idx @ + over - + + float-parse + + realnum-type +; + +: readbool ( -- bool-obj ) inc-parse-idx nextchar [char] f = if @@ -606,7 +704,7 @@ parse-idx-stack parse-idx-sp ! boolean-type ; -: readchar ( -- char-atom ) +: readchar ( -- char-obj ) inc-parse-idx inc-parse-idx @@ -709,7 +807,12 @@ parse-idx-stack parse-idx-sp ! eatspaces fixnum? if - readnum + readfixnum + exit + then + + realnum? if + readrealnum exit then @@ -765,24 +868,29 @@ parse-idx-stack parse-idx-sp ! eof? if inc-parse-idx - bold fg blue ." Moriturus te saluto." reset-term ." ok" cr + bold fg blue ." Moriturus te saluto." reset-term cr quit then \ 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 \ }}} \ ---- Eval ---- {{{ -defer eval - : self-evaluating? ( obj -- obj bool ) boolean-type istype? if true exit then fixnum-type istype? if true exit then + realnum-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 @@ -810,11 +918,23 @@ defer eval : 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 ; + cdr car + symbol-type istype? false = if car then +; : definition-val ( obj -- val ) - cdr cdr car ; + 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? ; @@ -881,6 +1001,21 @@ defer eval : 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? ; @@ -911,6 +1046,15 @@ defer eval 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 @@ -918,7 +1062,27 @@ defer eval endof compound-proc-type of - ." Compound procedures not yet implemented." + 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 @@ -966,7 +1130,15 @@ defer eval if-alternative then - 2swap ['] eval goto + 2swap + ['] eval goto-deferred + then + + lambda? if + 2dup lambda-parameters + 2swap lambda-body + 2rot make-procedure + exit then application? if @@ -987,9 +1159,9 @@ defer eval \ ---- Print ---- {{{ -defer print +: printfixnum ( fixnumobj -- ) drop 0 .R ; -: printnum ( numobj -- ) drop 0 .R ; +: printrealnum ( realnumobj -- ) drop float-print ; : printbool ( numobj -- ) drop if @@ -1050,8 +1222,12 @@ defer print : printprim ( primobj -- ) 2drop ." " ; +: printcomp ( primobj -- ) + 2drop ." " ; + :noname ( obj -- ) - fixnum-type istype? if printnum exit then + fixnum-type istype? if printfixnum exit then + realnum-type istype? if printrealnum exit then boolean-type istype? if printbool exit then character-type istype? if printchar exit then string-type istype? if printstring exit then @@ -1059,6 +1235,7 @@ defer print 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 @@ -1066,18 +1243,126 @@ defer print \ }}} +\ ---- 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 + +\ }}} + \ ---- 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 - global-env fetchobj eval + + global-env obj@ eval + fg cyan ." ; " print reset-term again ;