X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=blobdiff_plain;f=scheme.4th;h=f8dd0899d0e02aac9094648a03be84f1f10ee6f6;hp=3c5c6a95c90f863d54bc4e351c4e88e79a127acc;hb=3eaf389aa81bcfbf8dd64c89520925413d5c2390;hpb=13e038552e84df8c480b101b09e4c5a650bad2d0 diff --git a/scheme.4th b/scheme.4th index 3c5c6a9..f8dd089 100644 --- a/scheme.4th +++ b/scheme.4th @@ -3,6 +3,7 @@ scheme definitions include term-colours.4th include defer-is.4th +include catch-throw.4th include float.4th include debugging.4th @@ -11,7 +12,9 @@ defer read defer eval defer print -\ ------ Types ------ +defer collect-garbage + +\ ---- Types ---- {{{ variable nexttype 0 nexttype ! @@ -26,16 +29,54 @@ 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 = ; -\ ------ Cons cell memory ------ {{{ +\ }}} + +\ ---- 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 -1000 constant scheme-memsize create car-cells scheme-memsize allot create car-type-cells scheme-memsize allot create cdr-cells scheme-memsize allot @@ -53,13 +94,14 @@ variable nextfree : inc-nextfree nextfrees nextfree @ + @ + nextfree ! - dup scheme-memsize < if - nextfree ! - else - bold fg red - ." Out of memory! Aborting." - reset-term abort + nextfree @ scheme-memsize >= if + collect-garbage + then + + nextfree @ scheme-memsize >= if + unrecoverable-exception throw s" Out of memory!" then ; @@ -97,14 +139,12 @@ variable nextfree cdr-cells + ! ; -: caar car car ; -: cadr cdr car ; -: cdar car cdr ; -: cddr cdr cdr ; - : nil 0 nil-type ; : nil? nil-type istype? ; +: none 0 none-type ; +: none? none-type istype? ; + : objvar create nil swap , , ; : value@ ( objvar -- val ) @ ; @@ -133,58 +173,34 @@ variable nextfree \ }}} -\ ---- Garbage Collection ---- {{{ - -variable gc-enabled -false gc-enabled ! - -: gc-enable - true gc-enabled ! ; +\ ---- Port I/O ---- {{{ -: gc-disable - false gc-enabled ! ; +: fileport>fid ( fileport -- fid ) + drop ; -: gc-enabled? - gc-enabled @ ; +: fid>fileport ( fid -- fileport ) + fileport-type ; -: 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 +: open-input-file ( addr n -- fileport ) + r/o open-file drop fid>fileport ; -: pairlike-marked? ( obj -- obj bool ) - over nextfrees + 0= +: close-port ( fileport -- ) + fileport>fid close-file drop ; -: mark-pairlike ( obj -- obj ) - over nextfrees + 0 swap ! -; - -: gc-mark-obj ( obj -- ) - - pairlike? invert if 2drop exit then - pairlike-marked? if 2drop exit then - - mark-pairlike +objvar console-i/o-port +0 fileport-type console-i/o-port obj! - drop pair-type 2dup +objvar current-input-port +console-i/o-port obj@ current-input-port obj! - car recurse - cdr recurse -; +: read-port ( fileport -- obj ) + current-input-port obj! + read ; -: gc-sweep - scheme-memsize nextfree ! - 0 scheme-memsize 1- do - nextfrees i + @ 0<> if - nextfree @ nextfrees i + ! - i nextfree ! - then - -1 +loop ; +: read-console ( -- obj ) + console-i/o-port obj@ read-port ; \ }}} @@ -193,7 +209,7 @@ false gc-enabled ! objvar symbol-table : duplicate-charlist ( charlist -- copy ) - 2dup nil objeq? false = if + nil? false = if 2dup car 2swap cdr recurse cons then ; @@ -252,7 +268,7 @@ objvar symbol-table ; -: (create-symbol) ( addr n -- symbol-obj ) +: cstr>charlist ( addr n -- charlist ) dup 0= if 2drop nil else @@ -268,26 +284,25 @@ objvar symbol-table bl word count - (create-symbol) - drop symbol-type - - 2dup - - symbol-table obj@ - cons - symbol-table obj! + cstr>charlist + charlist>symbol create swap , , does> dup @ swap 1+ @ ; -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 +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 \ }}} @@ -347,7 +362,7 @@ objvar vals : get-vars-vals ( var env -- vars? vals? bool ) begin - 2dup nil objeq? false = + nil? false = while 2over 2over first-frame get-vars-vals-frame if @@ -370,7 +385,7 @@ hide vals get-vars-vals if 2swap 2drop car else - bold fg red ." Tried to read unbound variable." reset-term cr abort + recoverable-exception throw" Tried to read unbound variable." then ; @@ -380,7 +395,7 @@ hide vals 2swap 2drop ( val vals ) set-car! else - bold fg red ." Tried to set unbound variable." reset-term cr abort + recoverable-exception throw" Tried to set unbound variable." then ; @@ -403,6 +418,12 @@ objvar env 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! @@ -417,32 +438,21 @@ global-env obj! \ 2dup ." Defining primitive " type ." ..." cr - (create-symbol) - drop symbol-type - - 2dup - - symbol-table obj@ - cons - symbol-table obj! - + cstr>charlist + charlist>symbol + 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 + recoverable-exception throw" Too many arguments for primitive procedure." then else - -rot 2dup nil objeq? if - arg-count-error + -rot nil? if + recoverable-exception throw" Too few arguments for primitive procedure." then cdr rot 1- recurse @@ -456,11 +466,65 @@ global-env obj! : ensure-arg-type ( arg type -- arg ) istype? false = if - arg-type-error + recoverable-exception throw" Incorrect argument type for primitive procedure." then ; -include scheme-primitives.4th + +\ }}} + +\ ---- 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! +; \ }}} @@ -492,13 +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 ! ; @@ -515,12 +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? @@ -738,7 +817,7 @@ parse-idx-stack parse-idx-sp ! realnum-type ; -: readbool ( -- bool-atom ) +: readbool ( -- bool-obj ) inc-parse-idx nextchar [char] f = if @@ -752,7 +831,7 @@ parse-idx-stack parse-idx-sp ! boolean-type ; -: readchar ( -- char-atom ) +: readchar ( -- char-obj ) inc-parse-idx inc-parse-idx @@ -914,10 +993,25 @@ parse-idx-stack parse-idx-sp ! 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 + EOF character-type inc-parse-idx - bold fg blue ." Moriturus te saluto." reset-term cr - quit + exit then \ Anything else is parsed as a symbol @@ -942,6 +1036,7 @@ parse-idx-stack parse-idx-sp ! character-type istype? if true exit then string-type istype? if true exit then nil-type istype? if true exit then + none-type istype? if true exit then false ; @@ -958,7 +1053,96 @@ parse-idx-stack parse-idx-sp ! quote-symbol tagged-list? ; : quote-body ( quote-obj -- quote-body-obj ) - cadr ; + cdr car ; + +: 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 +; + +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 ) + + 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? ; @@ -969,19 +1153,34 @@ parse-idx-stack parse-idx-sp ! : make-lambda ( params body -- lambda-exp ) lambda-symbol -2rot cons cons ; -: definition-var ( obj -- var ) - cdr car - symbol-type istype? false = if car then +( 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 ; -: definition-val ( obj -- val ) - 2dup cdr car symbol-type istype? if - 2drop - cdr cdr car - else - cdr 2swap cdr cdr - make-lambda - then +: 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 ) @@ -993,20 +1192,6 @@ parse-idx-stack parse-idx-sp ! : 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-assignment ( obj env -- res ) 2swap 2over 2over ( env obj env obj ) @@ -1021,6 +1206,34 @@ parse-idx-stack parse-idx-sp ! 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? ; @@ -1030,10 +1243,10 @@ parse-idx-stack parse-idx-sp ! : if-consequent ( ifobj -- conseq ) cdr cdr car ; -: if-alternative ( ifobj -- alt|false ) +: if-alternative ( ifobj -- alt|none ) cdr cdr cdr - 2dup nil objeq? if - 2drop false + nil? if + 2drop none else car then ; @@ -1058,13 +1271,39 @@ parse-idx-stack parse-idx-sp ! : lambda-body ( obj -- body ) cdr cdr ; -: make-procedure ( params body env -- proc ) - nil - cons cons cons - drop compound-proc-type +: 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) +: application? ( obj -- obj bool ) pair-type istype? ; : operator ( obj -- operator ) @@ -1103,41 +1342,81 @@ parse-idx-stack parse-idx-sp ! : procedure-env ( proc -- body ) drop pair-type cdr cdr car ; -: apply ( proc args ) +( 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 + 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 ) + 2dup procedure-body ( argvals proc body ) + -2rot 2dup procedure-params ( body argvals proc argnames ) + -2rot procedure-env ( body argnames argvals procenv ) - 2swap ( env body ) + -2rot 2swap + flatten-proc-args + 2swap 2rot - begin - 2dup cdr 2dup nil objeq? false = - while - -2rot car 2over ( nextbody env exp env ) - eval - 2drop \ discard result - 2swap ( env nextbody ) - repeat + extend-env ( body env ) - 2drop ( env body ) - car 2swap ( exp env ) + eval-sequence R> drop ['] eval goto-deferred \ Tail call optimization endof - bold fg red ." Object not applicable. Aboring." reset-term cr - abort + 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 @@ -1152,6 +1431,11 @@ parse-idx-stack parse-idx-sp ! exit then + quasiquote? if + 2swap eval-quasiquote + exit + then + variable? if 2swap lookup-var exit @@ -1167,6 +1451,11 @@ parse-idx-stack parse-idx-sp ! exit then + macro-definition? if + 2swap eval-define-macro + exit + then + if? if 2over 2over if-predicate @@ -1189,18 +1478,44 @@ parse-idx-stack parse-idx-sp ! exit then + begin? if + begin-actions 2swap + eval-sequence + ['] eval goto-deferred + then + application? if - 2over 2over - operator 2swap eval - -2rot - operands 2swap list-of-vals - apply - exit + 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 - bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr - abort + recoverable-exception throw" Tried to evaluate object with unknown type." ; is eval \ }}} @@ -1231,7 +1546,7 @@ parse-idx-stack parse-idx-sp ! ; : (printstring) ( stringobj -- ) - nil-type istype? if 2drop exit then + nil? if 2drop exit then 2dup car drop dup case @@ -1273,6 +1588,12 @@ parse-idx-stack parse-idx-sp ! : printcomp ( primobj -- ) 2drop ." " ; +: printnone ( noneobj -- ) + 2drop ." Unspecified return value" ; + +: printport ( port -- ) + 2drop ." " ; + :noname ( obj -- ) fixnum-type istype? if printfixnum exit then realnum-type istype? if printrealnum exit then @@ -1284,30 +1605,206 @@ parse-idx-stack parse-idx-sp ! 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 - begin - cr bold fg green ." > " reset-term - read + enable-gc - global-env obj@ eval + begin + ['] repl-body catch + case + recoverable-exception of false endof + unrecoverable-exception of true endof - fg cyan ." ; " print reset-term - again + throw false + endcase + until ; forth definitions