X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=f8dd0899d0e02aac9094648a03be84f1f10ee6f6;hb=3eaf389aa81bcfbf8dd64c89520925413d5c2390;hp=75055ff09b6bd83fc2269d48317e5d650a277cf7;hpb=47b94d7af3449341b96f8e1b420c708c9a4c2fc2;p=scheme.forth.jl.git diff --git a/scheme.4th b/scheme.4th index 75055ff..f8dd089 100644 --- a/scheme.4th +++ b/scheme.4th @@ -3,24 +3,108 @@ scheme definitions include term-colours.4th include defer-is.4th +include catch-throw.4th +include float.4th -0 constant number-type -1 constant boolean-type -2 constant character-type -3 constant nil-type -4 constant pair-type -: istype? ( obj -- obj b ) +include debugging.4th + +defer read +defer eval +defer print + +defer collect-garbage + +\ ---- Types ---- {{{ + +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 none-type +make-type pair-type +make-type symbol-type +make-type primitive-proc-type +make-type compound-proc-type +make-type fileport-type +: istype? ( obj type -- obj bool ) over = ; -100 constant N -create car-cells N allot -create car-type-cells N allot -create cdr-cells N allot -create cdr-type-cells N allot +\ }}} + +\ ---- Exceptions ---- {{{ + +variable nextexception +1 nextexception ! +: make-exception + create nextexception @ , + 1 nextexception +! + does> @ ; + +make-exception recoverable-exception +make-exception unrecoverable-exception + +: display-exception-msg ( addr count -- ) + bold fg red + ." Exception: " + type + reset-term ; + +: throw" immediate + [compile] s" + + ['] rot , ['] dup , + + [compile] if + ['] -rot , + ['] display-exception-msg , + [compile] then + + ['] throw , +; + +\ }}} + +\ ---- List-structured memory ---- {{{ + +10000 constant scheme-memsize +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 + unrecoverable-exception throw s" Out of memory!" + then +; + : cons ( car-obj cdr-obj -- pair-obj ) cdr-type-cells nextfree @ + ! cdr-cells nextfree @ + ! @@ -28,8 +112,7 @@ variable nextfree car-cells nextfree @ + ! nextfree @ pair-type - - 1 nextfree +! + inc-nextfree ; : car ( pair-obj -- car-obj ) @@ -44,8 +127,408 @@ 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 + ! +; + +: nil 0 nil-type ; +: nil? nil-type istype? ; + +: none 0 none-type ; +: none? none-type istype? ; + +: objvar create nil swap , , ; + +: value@ ( objvar -- val ) @ ; +: type@ ( objvar -- type ) 1+ @ ; +: value! ( newval objvar -- ) ! ; +: type! ( newtype objvar -- ) 1+ ! ; +: obj! ( newobj objvar -- ) dup rot swap 1+ ! ! ; +: obj@ ( objvar -- obj ) dup @ swap 1+ @ ; + +: 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> +; + +\ }}} + +\ ---- Port I/O ---- {{{ + +: fileport>fid ( fileport -- fid ) + drop ; + +: fid>fileport ( fid -- fileport ) + fileport-type ; + +: open-input-file ( addr n -- fileport ) + r/o open-file drop fid>fileport +; + +: close-port ( fileport -- ) + fileport>fid close-file drop +; + +objvar console-i/o-port +0 fileport-type console-i/o-port obj! + +objvar current-input-port +console-i/o-port obj@ current-input-port obj! + +: read-port ( fileport -- obj ) + current-input-port obj! + read ; + +: read-console ( -- obj ) + console-i/o-port obj@ read-port ; + +\ }}} + +\ ---- Pre-defined symbols ---- {{{ + +objvar symbol-table + +: duplicate-charlist ( charlist -- copy ) + nil? 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! +; + + +: cstr>charlist ( addr n -- charlist ) + dup 0= if + 2drop nil + else + 2dup drop @ character-type 2swap + swap 1+ swap 1- + recurse + + cons + then +; + +: create-symbol ( -- ) + bl word + count + + cstr>charlist + charlist>symbol + + create swap , , + does> dup @ swap 1+ @ +; + +create-symbol quote quote-symbol +create-symbol quasiquote quasiquote-symbol +create-symbol unquote unquote-symbol +create-symbol unquote-splicing unquote-splicing-symbol +create-symbol define define-symbol +create-symbol define-macro define-macro-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 +create-symbol begin begin-symbol + +\ }}} + +\ ---- Environments ---- {{{ + +: enclosing-env ( env -- env ) + cdr ; + +: first-frame ( env -- frame ) + car ; + +: make-frame ( vars vals -- frame ) + cons ; + +: 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 + nil? 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 + recoverable-exception throw" Tried to read unbound variable." + 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 + recoverable-exception throw" Tried to set unbound variable." + 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 + +: make-procedure ( params body env -- proc ) + nil + cons cons cons + drop compound-proc-type +; + +objvar global-env +nil nil nil extend-env +global-env obj! + +\ }}} + +\ ---- Primitives ---- {{{ + +: make-primitive ( cfa -- ) + bl word + count + + \ 2dup ." Defining primitive " type ." ..." cr + + cstr>charlist + charlist>symbol + + rot primitive-proc-type ( var prim ) + global-env obj@ define-var +; + +: ensure-arg-count ( args n -- ) + dup 0= if + drop nil objeq? false = if + recoverable-exception throw" Too many arguments for primitive procedure." + then + else + -rot nil? if + recoverable-exception throw" Too few arguments for primitive procedure." + 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 + recoverable-exception throw" Incorrect argument type for primitive procedure." + then +; + + +\ }}} + +\ ---- Macros ---- {{{ + +objvar macro-table + +( Look up macro in macro table. Returns nil if + no macro is found. ) +: lookup-macro ( name_symbol -- proc ) + macro-table obj@ + + begin + nil? false = + while + 2over 2over + car car objeq? if + 2swap 2drop + car cdr + exit + then + + cdr + repeat + + 2swap 2drop +; + +: make-macro ( name_symbol params body env -- ) + make-procedure + + 2swap ( proc name_symbol ) + + macro-table obj@ + + begin + nil? false = + while + 2over 2over ( proc name table name table ) + car car objeq? if + 2swap 2drop ( proc table ) + car ( proc entry ) + set-cdr! + exit + then + + cdr + repeat + + 2drop + + 2swap cons + macro-table obj@ cons + macro-table obj! +; + +\ }}} -\ ---- Read ---- +\ ---- Read ---- {{{ variable parse-idx variable stored-parse-idx @@ -73,13 +556,24 @@ parse-idx-stack parse-idx-sp ! '\n' parse-str parse-str-span @ + ! 1 parse-str-span +! ; +: append-eof + 4 parse-str parse-str-span @ + ! + 1 parse-str-span +! ; + : empty-parse-str 0 parse-str-span ! 0 parse-idx ! ; : getline - parse-str 160 expect cr - span @ parse-str-span ! + current-input-port obj@ console-i/o-port obj@ objeq? if + parse-str 160 expect cr + span @ parse-str-span ! + else + parse-str 160 current-input-port obj@ fileport>fid read-line + drop swap parse-str-span ! + + parse-str-span @ 0= and if append-eof then + then append-newline 0 parse-idx ! ; @@ -96,12 +590,16 @@ parse-idx-stack parse-idx-sp ! charavailable? false = if getline then parse-str parse-idx @ + @ ; +: '\t' 9 ; : whitespace? ( -- bool ) nextchar BL = - nextchar '\n' = or ; + nextchar '\n' = + nextchar '\t' = + or or ; +: EOF 4 ; : eof? ( -- bool ) - nextchar 4 = ; + nextchar EOF = ; : delim? ( -- bool ) whitespace? @@ -109,12 +607,27 @@ 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 ) @@ -125,10 +638,23 @@ 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 @@ -138,13 +664,52 @@ 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 ) @@ -211,10 +776,15 @@ parse-idx-stack parse-idx-sp ! : pair? ( -- bool ) nextchar [char] ( = ; +: string? ( -- bool ) + nextchar [char] " = ; -: readnum ( -- num-atom ) - minus? dup if +: readfixnum ( -- num-atom ) + plus? minus? or if + minus? inc-parse-idx + else + false then 0 @@ -226,10 +796,28 @@ 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 ) +: readbool ( -- bool-obj ) inc-parse-idx nextchar [char] f = if @@ -243,7 +831,7 @@ parse-idx-stack parse-idx-sp ! boolean-type ; -: readchar ( -- char-atom ) +: readchar ( -- char-obj ) inc-parse-idx inc-parse-idx @@ -256,18 +844,13 @@ parse-idx-stack parse-idx-sp ! inc-parse-idx ; -defer read - -: readpair ( -- obj ) - eatspaces - - \ Empty lists - nextchar [char] ) = if +: readstring ( -- charlist ) + nextchar [char] " = if inc-parse-idx delim? false = if bold fg red - ." No delimiter following right paren. Aborting." cr + ." No delimiter following right double quote. Aborting." cr reset-term abort then @@ -276,16 +859,61 @@ defer read 0 nil-type exit then - \ Read first pair element - read - - \ Pairs - eatspaces - nextchar [char] . = if + nextchar [char] \ = if inc-parse-idx + nextchar case + [char] n of '\n' endof + [char] " of [char] " endof + [char] \ + endcase + else + nextchar + then + inc-parse-idx character-type - delim? false = if - bold fg red + recurse + + cons +; + +: readsymbol ( -- charlist ) + delim? if nil exit then + + nextchar inc-parse-idx character-type + + recurse + + cons +; + +: readpair ( -- pairobj ) + eatspaces + + \ Empty lists + nextchar [char] ) = if + inc-parse-idx + + delim? false = if + bold fg red + ." No delimiter following right paren. Aborting." cr + reset-term abort + then + + dec-parse-idx + + 0 nil-type exit + then + + \ Read first pair element + read + + \ Pairs + eatspaces + nextchar [char] . = if + inc-parse-idx + + delim? false = if + bold fg red ." No delimiter following '.'. Aborting." cr reset-term abort then @@ -305,8 +933,13 @@ defer read eatspaces - number? if - readnum + fixnum? if + readfixnum + exit + then + + realnum? if + readrealnum exit then @@ -320,6 +953,22 @@ defer read exit then + string? if + inc-parse-idx + + readstring + drop string-type + + nextchar [char] " <> if + bold red ." Missing closing double-quote." reset-term cr + abort + then + + inc-parse-idx + + exit + then + pair? if inc-parse-idx @@ -339,40 +988,543 @@ defer read exit then + nextchar [char] ' = if + inc-parse-idx + quote-symbol recurse nil cons cons exit + then + + nextchar [char] ` = if + inc-parse-idx + quasiquote-symbol recurse nil cons cons exit + then + + nextchar [char] , = if + inc-parse-idx + nextchar [char] @ = if + inc-parse-idx + unquote-splicing-symbol recurse nil cons cons exit + else + unquote-symbol recurse nil cons cons exit + then + then + eof? if - bold fg blue ." Moriturus te saluto." reset-term ." ok" cr - quit + EOF character-type + inc-parse-idx + exit 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 ) - number-type istype? if true exit then 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 - false ; + none-type istype? if true exit then + + false +; + +: tagged-list? ( obj tag-obj -- obj bool ) + 2over + pair-type istype? false = if + 2drop 2drop false + else + car objeq? + then ; + +: quote? ( obj -- obj bool ) + quote-symbol tagged-list? ; -: eval - \ self-evaluating? if - \ exit - \ then - exit +: quote-body ( quote-obj -- quote-body-obj ) + cdr car ; - bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr - abort +: quasiquote? ( obj -- obj bool ) + quasiquote-symbol tagged-list? ; + +: unquote? ( obj -- obj bool ) + unquote-symbol tagged-list? ; + +: unquote-splicing? ( obj -- obj bool ) + unquote-splicing-symbol tagged-list? ; + +: eval-unquote ( env obj -- res ) + cdr ( env args ) + + nil? if + recoverable-exception throw" no arguments to unquote." + then + + 2dup cdr + nil? false = if + recoverable-exception throw" too many arguments to unquote." + then + + 2drop car 2swap eval +; + +( Create a new list from elements of l1 consed on to l2 ) +: join-lists ( l2 l1 -- l3 ) + nil? if 2drop exit then + + 2dup car + -2rot cdr + recurse cons ; -\ ---- Print ---- +defer eval-quasiquote-item +: eval-quasiquote-pair ( env obj -- res ) + 2over 2over ( env obj env obj ) + + cdr eval-quasiquote-item + + -2rot car ( cdritem env objcar ) -: printnum ( numobj -- ) drop 0 .R ; + unquote-splicing? if + eval-unquote ( cdritems caritem ) + + 2swap nil? if + 2drop + else + 2swap join-lists + then + else + eval-quasiquote-item ( cdritems caritem ) + 2swap cons + then + +; + +:noname ( env obj ) + nil? if + 2swap 2drop exit + then + + unquote? if + eval-unquote exit + then + + pair-type istype? if + eval-quasiquote-pair exit + then + + 2swap 2drop +; is eval-quasiquote-item + +: eval-quasiquote ( obj env -- res ) + 2swap cdr ( env args ) + + nil? if + recoverable-exception throw" no arguments to quasiquote." + then + + 2dup cdr ( env args args-cdr ) + nil? false = if + recoverable-exception throw" too many arguments to quasiquote." + then + + 2drop car ( env arg ) + + eval-quasiquote-item +; + +: 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 ; + +( 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 + + 2swap car +; + +: eval-definition ( obj env -- res ) + 2dup 2rot ( env env obj ) + definition-var-val ( env env var val ) + 2rot eval ( env var val ) + + 2rot ( var val env ) + define-var + + ok-symbol +; + +: assignment? ( obj -- obj bool ) + set!-symbol tagged-list? ; + +: assignment-var ( obj -- var ) + cdr car ; + +: assignment-val ( obj -- val ) + cdr cdr car ; + +: 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 +; + +: macro-definition? ( obj -- obj bool ) + define-macro-symbol tagged-list? ; + +: macro-definition-name ( exp -- mname ) + cdr car car ; + +: macro-definition-params ( exp -- params ) + cdr car cdr ; + +: macro-definition-body ( exp -- body ) + cdr cdr ; + +objvar env +: eval-define-macro ( obj env -- res ) + env obj! + + 2dup macro-definition-name 2swap ( name obj ) + 2dup macro-definition-params 2swap ( name params obj ) + macro-definition-body ( name params body ) + + env obj@ ( name params body env ) + + make-macro + + ok-symbol +; +hide env + +: 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|none ) + cdr cdr cdr + nil? if + 2drop none + 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 ; + +: 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 + is returned to allow for tail optimization. ) + + 2swap ( env explist ) + + \ Abort on empty list + nil? if + 2drop none + 2swap exit + then + + begin + 2dup cdr ( env explist nextexplist ) + nil? false = + while + -2rot car 2over ( nextexplist env exp env ) + eval + 2drop \ discard result + 2swap ( env nextexplist ) + repeat + + 2drop car 2swap ( finalexp env ) +; + +: 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 ; + +( Ensure terminating symbol arg name is handled + specially to allow for variadic procedures. ) +: flatten-proc-args ( argvals argnames -- argvals' argnames' ) + nil? if + 2over nil? false = if + recoverable-exception throw" Too many arguments for compound procedure." + else + 2drop + then + exit + then + + symbol-type istype? if + nil cons + 2swap + nil cons + 2swap + exit + then + + 2over + nil? if + recoverable-exception throw" Too few arguments for compound procedure." + else + cdr + then + + 2over cdr + + recurse ( argvals argnames argvals'' argnames'' ) + 2rot car 2swap cons ( argvals argvals'' argnames' ) + 2rot car 2rot cons ( argnames' argvals' ) + 2swap +; + +: apply ( proc argvals -- result ) + 2swap dup case + primitive-proc-type of + drop execute + endof + + compound-proc-type of + 2dup procedure-body ( argvals proc body ) + -2rot 2dup procedure-params ( body argvals proc argnames ) + -2rot procedure-env ( body argnames argvals procenv ) + + -2rot 2swap + flatten-proc-args + 2swap 2rot + + extend-env ( body env ) + + eval-sequence + + R> drop ['] eval goto-deferred \ Tail call optimization + endof + + recoverable-exception throw" Object not applicable." + 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 + + self-evaluating? if + 2swap 2drop + exit + then + + quote? if + quote-body + 2swap 2drop + exit + then + + quasiquote? if + 2swap eval-quasiquote + exit + then + + variable? if + 2swap lookup-var + exit + then + + definition? if + 2swap eval-definition + exit + then + + assignment? if + 2swap eval-assignment + exit + then + + macro-definition? if + 2swap eval-define-macro + 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 + + 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 + + ( env exp env opname mproc ) + 2swap 2drop -2rot 2drop cdr ( env mproc body ) + + macro-expand + + 2swap + ['] eval goto-deferred + else + \ Regular function application + + 2drop ( env exp env opname ) + + 2swap eval ( env exp proc ) + + -2rot ( proc env exp ) + operands 2swap ( proc operands env ) + list-of-vals ( proc argvals ) + + apply + exit + then + then + + recoverable-exception throw" Tried to evaluate object with unknown type." +; is eval + +\ }}} + +\ ---- Print ---- {{{ + +: printfixnum ( fixnumobj -- ) drop 0 .R ; + +: printrealnum ( realnumobj -- ) drop float-print ; : printbool ( numobj -- ) drop if @@ -393,44 +1545,268 @@ defer read endcase ; +: (printstring) ( stringobj -- ) + nil? if 2drop exit then + + 2dup car drop dup + case + '\n' of ." \n" drop endof + [char] \ of ." \\" drop endof + [char] " of [char] \ emit [char] " emit drop endof + emit + endcase + + cdr recurse +; +: printstring ( stringobj -- ) + [char] " emit + (printstring) + [char] " emit ; + +: printsymbol ( symbolobj -- ) + nil-type istype? if 2drop exit then + + 2dup car drop emit + cdr recurse +; + : printnil ( nilobj -- ) - drop ." ()" ; + 2drop ." ()" ; -defer print : printpair ( pairobj -- ) 2dup car print cdr - nil-type istype? if 2drop ." )" exit then + nil-type istype? if 2drop exit then pair-type istype? if space recurse exit then ." . " print ; +: printprim ( primobj -- ) + 2drop ." " ; + +: printcomp ( primobj -- ) + 2drop ." " ; + +: printnone ( noneobj -- ) + 2drop ." Unspecified return value" ; + +: printport ( port -- ) + 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 + none-type istype? if printnone exit then - bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr - abort + recoverable-exception throw" Tried to print object with unknown type." ; is 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 + macro-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 + +\ }}} + +\ ---- Loading files ---- {{{ + +: charlist>cstr ( charlist addr -- n ) + + dup 2swap ( origaddr addr charlist ) + + begin + nil? false = + while + 2dup cdr 2swap car + drop ( origaddr addr charlist char ) + -rot 2swap ( origaddr charlist addr char ) + over ! + 1+ -rot ( origaddr nextaddr charlist ) + repeat + + 2drop ( origaddr finaladdr ) + swap - +; + +: load ( addr n -- finalResult ) + open-input-file + + empty-parse-str + + ok-symbol ( port res ) + + begin + 2over read-port ( port res obj ) + + 2dup EOF character-type objeq? if + 2drop 2swap close-port + exit + then + + 2swap 2drop ( port obj ) + + global-env obj@ eval ( port res ) + again +; + +\ }}} + +\ ---- Standard Library ---- {{{ + + include scheme-primitives.4th + + s" scheme-library.scm" load 2drop + +\ }}} + \ ---- REPL ---- +( REPL calls REPL-BODY in a loop until repl-body returns true. ) +: repl-body ( -- bool ) + cr bold fg green ." > " reset-term + + read-console + + 2dup EOF character-type objeq? if + 2drop + bold fg blue ." Moriturus te saluto." reset-term cr + true exit + then + + global-env obj@ eval + + fg cyan ." ; " print reset-term + + false +; + : 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 - eval - fg cyan ." ; " print reset-term - again + ['] repl-body catch + case + recoverable-exception of false endof + unrecoverable-exception of true endof + + throw false + endcase + until ; forth definitions + +\ vim:fdm=marker