X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=3e7b827ad54adfe6a7a507f53bbadecb508ad821;hb=52243a65c93217c43cad6146bf38708fab52c7fd;hp=4df51d08bc3be9441c848ab99be4bfad949f50ee;hpb=c48d0766c23a3f5218e6fedf99250c727bf75dbc;p=scheme.forth.jl.git diff --git a/scheme.4th b/scheme.4th index 4df51d0..3e7b827 100644 --- a/scheme.4th +++ b/scheme.4th @@ -3,30 +3,58 @@ scheme definitions include term-colours.4th include defer-is.4th +include float.4th + +include debugging.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 @ , + 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 = ; -\ ------ Memory ------ +\ ------ 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 create cdr-type-cells N allot +create nextfrees N allot +:noname + N 0 do + i 1+ nextfrees i + ! + loop +; execute + variable nextfree 0 nextfree ! +: inc-nextfree + nextfrees nextfree @ + @ + nextfree ! ; + : cons ( car-obj cdr-obj -- pair-obj ) cdr-type-cells nextfree @ + ! cdr-cells nextfree @ + ! @@ -34,8 +62,7 @@ variable nextfree car-cells nextfree @ + ! nextfree @ pair-type - - 1 nextfree +! + inc-nextfree ; : car ( pair-obj -- car-obj ) @@ -50,6 +77,18 @@ variable nextfree cdr-type-cells + @ ; +: set-car! ( obj pair-obj -- ) + drop dup + rot swap car-type-cells + ! + car-cells + ! +; + +: set-cdr! ( obj pair-obj -- ) + drop dup + rot swap cdr-type-cells + ! + cdr-cells + ! +; + : caar car car ; : cadr cdr car ; : cdar car cdr ; @@ -58,22 +97,154 @@ variable nextfree : nil 0 nil-type ; : nil? nil-type istype? ; -: objvar create 0 , 0 , ; +: objvar create nil swap , , ; : value@ ( objvar -- val ) @ ; : type@ ( objvar -- type ) 1+ @ ; : value! ( newval objvar -- ) ! ; : type! ( newtype objvar -- ) 1+ ! ; -: setobj ( newobj objvar -- ) dup rot swap 1+ ! ! ; -: fetchobj ( objvar -- obj ) dup @ swap 1+ @ ; - -objvar symbol-table -nil symbol-table setobj +: obj! ( newobj objvar -- ) dup rot swap 1+ ! ! ; +: obj@ ( objvar -- obj ) dup @ swap 1+ @ ; : objeq? ( obj obj -- bool ) rot = -rot = and ; -\ ---- Pre-defined symbols ---- +: 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> +; + +\ }}} + +\ ---- Garbage Collection ---- {{{ + +variable gc-enabled +false gc-enabled ! + +: gc-enable + true gc-enabled ! ; + +: gc-disable + 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 + + false +; + +: pairlike-marked? ( obj -- obj bool ) + over nextfrees + 0= +; + +: mark-pairlike ( obj -- obj ) + over nextfrees + 0 swap ! +; + +: gc-mark-obj ( obj -- ) + + pairlike? if + pairlike-marked? if 2drop exit then + + mark-pairlike + + 2dup + + car recurse + cdr recurse + else + 2drop + then +; + +: gc-sweep + N nextfree ! + 0 N 1- do + nextfrees i + @ 0<> if + nextfree @ nextfrees i + ! + i nextfree ! + then + -1 +loop ; + +\ }}} + +\ ---- 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 @@ -96,17 +267,198 @@ nil symbol-table setobj 2dup - symbol-table fetchobj + symbol-table obj@ cons - symbol-table setobj + symbol-table obj! create swap , , does> dup @ swap 1+ @ ; -create-symbol quote quote +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 ---- {{{ + +: enclosing-env ( env -- env ) + cdr ; + +: first-frame ( env -- frame ) + car ; + +: make-frame ( vars vals -- frame ) + cons ; -\ ---- Read ---- +: frame-vars ( frame -- vars ) + car ; + +: frame-vals ( frame -- vals ) + cdr ; + +: add-binding ( var val frame -- ) + 2swap 2over frame-vals cons + 2over set-cdr! + 2swap 2over frame-vars cons + 2swap set-car! +; + +: extend-env ( vars vals env -- env ) + >R >R + make-frame + R> R> + cons +; + +objvar vars +objvar vals + +: get-vars-vals-frame ( var frame -- bool ) + 2dup frame-vars vars obj! + frame-vals vals obj! + + begin + vars obj@ nil objeq? false = + while + 2dup vars obj@ car objeq? if + 2drop true + exit + then + + vars obj@ cdr vars obj! + vals obj@ cdr vals obj! + repeat + + 2drop false +; + +: get-vars-vals ( var env -- vars? vals? bool ) + + begin + 2dup nil objeq? false = + while + 2over 2over first-frame + get-vars-vals-frame if + 2drop 2drop + vars obj@ vals obj@ true + exit + then + + enclosing-env + repeat + + 2drop 2drop + false +; + +hide vars +hide vals + +: lookup-var ( var env -- val ) + get-vars-vals if + 2swap 2drop car + else + bold fg red ." Tried to read unbound variable." reset-term cr abort + then +; + +: set-var ( var val env -- ) + >R >R 2swap R> R> ( val var env ) + get-vars-vals if + 2swap 2drop ( val vals ) + set-car! + else + bold fg red ." Tried to set unbound variable." reset-term cr abort + then +; + +objvar env + +: define-var ( var val env -- ) + env obj! + + 2over env obj@ ( var val var env ) + get-vars-vals if + 2swap 2drop ( var val vals ) + set-car! + 2drop + else + env obj@ + first-frame ( var val frame ) + add-binding + then +; + +hide env + +objvar global-env +nil nil nil extend-env +global-env obj! + +\ }}} + +\ ---- Primitives ---- {{{ + +: make-primitive ( cfa -- ) + bl word + count + + \ 2dup ." Defining primitive " type ." ..." cr + + (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 ---- {{{ variable parse-idx variable stored-parse-idx @@ -170,12 +522,27 @@ 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 ) @@ -186,10 +553,23 @@ 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 @@ -199,13 +579,52 @@ 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 ) @@ -275,33 +694,12 @@ parse-idx-stack parse-idx-sp ! : string? ( -- bool ) nextchar [char] " = ; -: initial? ( -- bool ) - nextchar [char] A >= nextchar [char] Z <= and if true exit then - nextchar [char] a >= nextchar [char] z <= and if true exit then - nextchar [char] * = if true exit then - nextchar [char] / = if true exit then - nextchar [char] > = if true exit then - nextchar [char] < = if true exit then - nextchar [char] = = if true exit then - nextchar [char] ? = if true exit then - nextchar [char] ! = if true exit then - false -; - -: symbol? ( -- bool ) - initial? if true exit then - nextchar [char] + = - nextchar [char] - = or if - inc-parse-idx - delim? if dec-parse-idx true exit then - dec-parse-idx - then - false -; - -: readnum ( -- num-atom ) - minus? dup if +: readfixnum ( -- num-atom ) + plus? minus? or if + minus? inc-parse-idx + else + false then 0 @@ -313,7 +711,25 @@ parse-idx-stack parse-idx-sp ! swap if negate then - number-type + fixnum-type +; + +: 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-atom ) @@ -385,62 +801,6 @@ 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 @@ -488,8 +848,13 @@ defer read eatspaces - number? if - readnum + fixnum? if + readfixnum + exit + then + + realnum? if + readrealnum exit then @@ -505,6 +870,7 @@ defer read string? if inc-parse-idx + readstring drop string-type @@ -514,11 +880,7 @@ defer read then inc-parse-idx - exit - then - symbol? if - readsymbol charlist>symbol exit then @@ -543,26 +905,34 @@ defer read nextchar [char] ' = if inc-parse-idx - quote recurse nil cons cons exit + quote-symbol recurse nil cons cons exit then eof? if - bold fg blue ." Moriturus te saluto." reset-term ." ok" cr + inc-parse-idx + bold fg blue ." Moriturus te saluto." reset-term cr quit then - bold fg red ." Error parsing string starting at character '" - nextchar emit - ." '. Aborting." reset-term cr - abort + \ 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 ---- +\ }}} + +\ ---- 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 + 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 @@ -579,28 +949,261 @@ defer read then ; : quote? ( obj -- obj bool ) - quote tagged-list? ; + quote-symbol tagged-list? ; : quote-body ( quote-obj -- quote-body-obj ) cadr ; + +: variable? ( obj -- obj bool ) + symbol-type istype? ; + +: 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? ; + +: 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 ) + + 2swap definition-var 2swap ( env var val ) + + 2rot ( var val env ) + define-var + + ok-symbol +; -: eval +: 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 + 2swap 2drop exit then quote? if quote-body + 2swap 2drop + exit + then + + variable? if + 2swap lookup-var + 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 + +\ }}} -\ ---- Print ---- +\ ---- Print ---- {{{ -: printnum ( numobj -- ) drop 0 .R ; +: printfixnum ( fixnumobj -- ) drop 0 .R ; + +: printrealnum ( realnumobj -- ) drop float-print ; : printbool ( numobj -- ) drop if @@ -649,7 +1252,6 @@ defer read : printnil ( nilobj -- ) 2drop ." ()" ; -defer print : printpair ( pairobj -- ) 2dup car print @@ -659,33 +1261,49 @@ defer print ." . " print ; +: printprim ( primobj -- ) + 2drop ." " ; + +: printcomp ( primobj -- ) + 2drop ." " ; + :noname ( obj -- ) - number-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 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 ; is print +\ }}} + \ ---- REPL ---- : repl cr ." Welcome to scheme.forth.jl!" cr ." Use Ctrl-D to exit." cr + empty-parse-str begin cr bold fg green ." > " reset-term read - eval + + global-env obj@ eval + fg cyan ." ; " print reset-term again ; forth definitions + +\ vim:fdm=marker