X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=blobdiff_plain;f=scheme.4th;h=f8dd0899d0e02aac9094648a03be84f1f10ee6f6;hp=08b4bcd070b0cc912eb283b72479a7da33f9a8db;hb=3eaf389aa81bcfbf8dd64c89520925413d5c2390;hpb=4d9d90cad9c4280d93d6bf67f2083ef9d3c8235f diff --git a/scheme.4th b/scheme.4th index 08b4bcd..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 @@ -13,7 +14,7 @@ defer print defer collect-garbage -\ ------ Types ------ +\ ---- Types ---- {{{ variable nexttype 0 nexttype ! @@ -28,6 +29,7 @@ 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 @@ -36,7 +38,42 @@ make-type fileport-type : istype? ( obj type -- obj bool ) over = ; -\ ------ List-structured 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 @@ -64,9 +101,7 @@ variable nextfree then nextfree @ scheme-memsize >= if - fg red bold - ." Out of memory! Aborting." - reset-term abort + unrecoverable-exception throw s" Out of memory!" then ; @@ -104,14 +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 ) @ ; @@ -176,7 +209,7 @@ console-i/o-port obj@ current-input-port obj! objvar symbol-table : duplicate-charlist ( charlist -- copy ) - 2dup nil objeq? false = if + nil? false = if 2dup car 2swap cdr recurse cons then ; @@ -235,7 +268,7 @@ objvar symbol-table ; -: cstr>charlist ( addr n -- symbol-obj ) +: cstr>charlist ( addr n -- charlist ) dup 0= if 2drop nil else @@ -252,26 +285,24 @@ objvar symbol-table count cstr>charlist - drop symbol-type - - 2dup - - symbol-table obj@ - cons - symbol-table obj! + 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 begin begin-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 \ }}} @@ -331,7 +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 @@ -354,7 +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 ; @@ -364,7 +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 ; @@ -387,12 +418,116 @@ 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! \ }}} +\ ---- 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 ---- {{{ variable parse-idx @@ -858,6 +993,21 @@ 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 @@ -886,6 +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 ; @@ -902,7 +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? ; @@ -913,19 +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 ) @@ -937,20 +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 ) @@ -965,6 +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? ; @@ -974,10 +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 ; @@ -1002,12 +1271,6 @@ 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? ; @@ -1022,11 +1285,14 @@ parse-idx-stack parse-idx-sp ! 2swap ( env explist ) \ Abort on empty list - 2dup nil objeq? if 2swap exit then + nil? if + 2drop none + 2swap exit + then begin 2dup cdr ( env explist nextexplist ) - 2dup nil objeq? false = + nil? false = while -2rot car 2over ( nextexplist env exp env ) eval @@ -1037,7 +1303,7 @@ parse-idx-stack parse-idx-sp ! 2drop car 2swap ( finalexp env ) ; -: application? ( obj -- obj bool) +: application? ( obj -- obj bool ) pair-type istype? ; : operator ( obj -- operator ) @@ -1076,16 +1342,55 @@ 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 ) + 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 ) @@ -1094,11 +1399,24 @@ parse-idx-stack parse-idx-sp ! 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 @@ -1113,6 +1431,11 @@ parse-idx-stack parse-idx-sp ! exit then + quasiquote? if + 2swap eval-quasiquote + exit + then + variable? if 2swap lookup-var exit @@ -1128,6 +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 @@ -1151,21 +1479,43 @@ parse-idx-stack parse-idx-sp ! then begin? if - \ TODO + 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 \ }}} @@ -1196,7 +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 @@ -1238,6 +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 @@ -1249,9 +1605,9 @@ 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 \ }}} @@ -1343,6 +1699,7 @@ variable gc-stack-depth 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 @@ -1359,61 +1716,6 @@ variable gc-stack-depth \ }}} -\ ---- Primitives ---- {{{ - -: make-primitive ( cfa -- ) - bl word - count - - \ 2dup ." Defining primitive " type ." ..." cr - - cstr>charlist - 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 - -\ }}} - \ ---- Loading files ---- {{{ : charlist>cstr ( charlist addr -- n ) @@ -1421,7 +1723,7 @@ include scheme-primitives.4th dup 2swap ( origaddr addr charlist ) begin - 2dup nil objeq? false = + nil? false = while 2dup cdr 2swap car drop ( origaddr addr charlist char ) @@ -1455,19 +1757,37 @@ include scheme-primitives.4th again ; -:noname ( args -- finalResult ) - 2dup 1 ensure-arg-count - car string-type ensure-arg-type +\ }}} - drop pair-type - pad charlist>cstr - pad swap load -; make-primitive load +\ ---- 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 @@ -1477,18 +1797,14 @@ include scheme-primitives.4th enable-gc begin - cr bold fg green ." > " reset-term - read-console + ['] repl-body catch + case + recoverable-exception of false endof + unrecoverable-exception of true endof - 2dup EOF character-type objeq? if - bold fg blue ." Moriturus te saluto." reset-term cr - exit - then - - global-env obj@ eval - - fg cyan ." ; " print reset-term - again + throw false + endcase + until ; forth definitions