X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=9d86461accd46f972012b8663bbc2c79a32fbfad;hb=8a9d83b586844a04f7ee19f98b56f460063bdcad;hp=3f57b1f084180d15b10b90a95efe8a4849206abe;hpb=22c0956408483a13192e8eea0f3e78b75459d66d;p=scheme.forth.jl.git diff --git a/scheme.4th b/scheme.4th index 3f57b1f..9d86461 100644 --- a/scheme.4th +++ b/scheme.4th @@ -6,17 +6,18 @@ include defer-is.4th \ ------ Types ------ -0 constant number-type +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-type : istype? ( obj type -- obj bool ) over = ; -\ ------ Cons cell memory ------ +\ ------ Cons cell memory ------ {{{ 1000 constant N create car-cells N allot @@ -82,10 +83,86 @@ variable nextfree : 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> +; + +\ }}} + +\ ---- 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 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 +; + + : (create-symbol) ( addr n -- symbol-obj ) dup 0= if 2drop nil @@ -115,13 +192,15 @@ objvar symbol-table does> dup @ swap 1+ @ ; -create-symbol quote quote-symbol -create-symbol define define-symbol -create-symbol set! set!-symbol +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 -\ ---- Environments ---- +\ }}} -objvar global-env +\ ---- Environments ---- {{{ : enclosing-env ( env -- env ) cdr ; @@ -140,9 +219,9 @@ objvar global-env : add-binding ( var val frame -- ) 2swap 2over frame-vals cons - 2over set-car! + 2over set-cdr! 2swap 2over frame-vars cons - swap set-cdr! + 2swap set-car! ; : extend-env ( vars vals env -- env ) @@ -155,7 +234,7 @@ objvar global-env objvar vars objvar vals -: lookup-var-frame ( var frame -- val? bool ) +: get-vars-vals-frame ( var frame -- bool ) 2dup frame-vars vars setobj frame-vals vals setobj @@ -163,8 +242,7 @@ objvar vals vars fetchobj nil objeq? false = while 2dup vars fetchobj car objeq? if - 2drop - vals fetchobj car true + 2drop true exit then @@ -175,67 +253,127 @@ objvar vals 2drop false ; -: lookup-var ( var env -- val ) +: get-vars-vals ( var env -- vars? vals? bool ) + begin 2dup nil objeq? false = while 2over 2over first-frame - lookup-var-frame if - -rot 2drop -rot 2drop + get-vars-vals-frame if + 2drop 2drop + vars fetchobj vals fetchobj true exit then enclosing-env repeat - bold fg red ." Unbound variable. Aborting." reset-term cr - abort + 2drop 2drop + false ; -objvar val +hide vars +hide vals -: set-var-frame ( var frame -- ) - 2dup frame-vars vars setobj - frame-vals vals setobj +: 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 +; - begin - vars fetchobj nil objeq? false = - while - 2dup vars fetchobj car objeq? if - 2drop - \ *** TODO *** - 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 +; - vars fetchobj cdr vars setobj - vals fetchobj cdr vals setobj - repeat +objvar env + +: define-var ( var val env -- ) + env setobj + + 2over env fetchobj ( var val var env ) + get-vars-vals if + 2swap 2drop ( var val vals ) + set-car! + 2drop + else + env fetchobj + first-frame ( var val frame ) + add-binding + then ; +hide env -: set-var ( var val env -- ) +objvar global-env +nil nil nil extend-env +global-env setobj + +\ }}} + +\ ---- Primitives ---- {{{ - 2swap val setobj +: make-primitive ( cfa -- ) + bl word + count + + (create-symbol) + drop symbol-type - begin - 2dup nil objeq? false = - while - 2over 2over first-frame - set-var-frame if - exit + 2dup + + symbol-table fetchobj + cons + symbol-table setobj + + rot primitive-type ( var prim ) + global-env fetchobj 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 +; - enclosing-env - repeat +: arg-type-error + bold fg red ." Incorrect argument type." reset-term cr + abort +; - bold fg red ." Unbound variable. Aborting." reset-term cr - abort +: ensure-arg-type ( arg type -- arg ) + istype? false = if + arg-type-error + then ; -hide vars -hide vals -hide val +include scheme-primitives.4th + +\ }}} -\ ---- Read ---- +\ ---- Read ---- {{{ + +defer read variable parse-idx variable stored-parse-idx @@ -299,12 +437,27 @@ 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 ) @@ -315,10 +468,23 @@ 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 @@ -405,8 +571,11 @@ parse-idx-stack parse-idx-sp ! nextchar [char] " = ; : readnum ( -- num-atom ) - minus? dup if + plus? minus? or if + minus? inc-parse-idx + else + false then 0 @@ -418,7 +587,7 @@ parse-idx-stack parse-idx-sp ! swap if negate then - number-type + fixnum-type ; : readbool ( -- bool-atom ) @@ -490,62 +659,6 @@ 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 @@ -593,7 +706,7 @@ defer read eatspaces - number? if + fixnum? if readnum exit then @@ -610,6 +723,7 @@ defer read string? if inc-parse-idx + readstring drop string-type @@ -619,6 +733,7 @@ defer read then inc-parse-idx + exit then @@ -656,11 +771,15 @@ defer read ; is read -\ ---- Eval ---- +\ }}} + +\ ---- Eval ---- {{{ + +defer 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 character-type istype? if true exit then string-type istype? if true exit then nil-type istype? if true exit then @@ -681,8 +800,115 @@ defer read : quote-body ( quote-obj -- quote-body-obj ) cadr ; + +: variable? ( obj -- obj bool ) + symbol-type istype? ; + +: definition? ( obj -- obj bool ) + define-symbol tagged-list? ; + +: definition-var ( obj -- var ) + cdr car ; + +: definition-val ( obj -- val ) + cdr cdr car ; + +: assignment? ( obj -- obj bool ) + set!-symbol tagged-list? ; + +: assignment-var ( obj -- var ) + cdr car ; -: eval ( obj env -- result ) +: 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 ) + 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 ; + +: 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 +; + +:noname ( obj env -- result ) 2swap self-evaluating? if @@ -696,11 +922,60 @@ defer read 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 + then + + application? if + 2over 2over + operator 2swap eval + + primitive-type istype? false = if + bold fg red ." Object not applicable. Aboring." reset-term cr + abort + then + + -2rot + operands 2swap list-of-vals + + 2swap drop execute + exit + then + bold fg red ." Error evaluating expression - unrecognized type. Aborting." reset-term cr abort -; +; is eval + +\ }}} -\ ---- Print ---- +\ ---- Print ---- {{{ + +defer print : printnum ( numobj -- ) drop 0 .R ; @@ -751,7 +1026,6 @@ defer read : printnil ( nilobj -- ) 2drop ." ()" ; -defer print : printpair ( pairobj -- ) 2dup car print @@ -761,19 +1035,25 @@ defer print ." . " print ; +: printprim ( primobj -- ) + 2drop ." " ; + :noname ( obj -- ) - number-type istype? if printnum exit then + fixnum-type istype? if printnum 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-type istype? if printprim exit then bold fg red ." Error printing expression - unrecognized type. Aborting" reset-term cr abort ; is print +\ }}} + \ ---- REPL ---- : repl @@ -791,3 +1071,5 @@ defer print ; forth definitions + +\ vim:fdm=marker