X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?a=blobdiff_plain;f=scheme.4th;h=1953cf98cf0ec004d9bbbe7c4a54acc96b93d4f6;hb=dc6e0cea1e1e982da8029c94d78ee66ab7e8fd82;hp=3014bea6d167d46dd71bd4b1c49dca5651521f61;hpb=3b232d28647991c3b6fd852ff4225a1416746cf6;p=scheme.forth.jl.git diff --git a/scheme.4th b/scheme.4th index 3014bea..1953cf9 100644 --- a/scheme.4th +++ b/scheme.4th @@ -6,13 +6,14 @@ 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 = ; @@ -82,6 +83,20 @@ variable nextfree : 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> +; + \ }}} \ ---- Pre-defined symbols ---- {{{ @@ -121,13 +136,12 @@ 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 - : enclosing-env ( env -- env ) cdr ; @@ -145,9 +159,9 @@ 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 ) @@ -185,7 +199,7 @@ objvar vals 2dup nil objeq? false = while 2over 2over first-frame - lookup-var-frame if + get-vars-vals-frame if 2drop 2drop vars fetchobj vals fetchobj true exit @@ -205,7 +219,7 @@ hide vals get-vars-vals if 2swap 2drop car else - bold fg red ." Tried to read unbound variable." reset-term abort + bold fg red ." Tried to read unbound variable." reset-term cr abort then ; @@ -215,22 +229,22 @@ hide vals 2swap 2drop ( val vals ) set-car! else - bold fg red ." Tried to set unbound variable." reset-term abort + bold fg red ." Tried to set unbound variable." reset-term cr abort then ; objvar env : define-var ( var val env -- ) - env objset + env setobj - 2over env objfetch ( var val var env ) + 2over env fetchobj ( var val var env ) get-vars-vals if 2swap 2drop ( var val vals ) set-car! 2drop else - env objfetch + env fetchobj first-frame ( var val frame ) add-binding then @@ -238,10 +252,58 @@ objvar env hide env +objvar global-env +nil nil nil extend-env +global-env setobj + +\ }}} + +\ ---- Primitives ---- {{{ + +: make-primitive ( cfa -- ) + bl word + count + + (create-symbol) + drop symbol-type + + 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 +; + +include scheme-primitives.4th + \ }}} \ ---- Read ---- {{{ +defer read + variable parse-idx variable stored-parse-idx create parse-str 161 allot @@ -320,10 +382,20 @@ parse-idx-stack parse-idx-sp ! : minus? ( -- bool ) nextchar [char] - = ; -: number? ( -- bool ) - digit? minus? or false = if - false - exit +: fixnum? ( -- bool ) + minus? 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 @@ -423,7 +495,7 @@ parse-idx-stack parse-idx-sp ! swap if negate then - number-type + fixnum-type ; : readbool ( -- bool-atom ) @@ -549,8 +621,6 @@ parse-idx-stack parse-idx-sp ! symbol-table setobj ; -defer read - : readpair ( -- pairobj ) eatspaces @@ -598,7 +668,7 @@ defer read eatspaces - number? if + fixnum? if readnum exit then @@ -667,9 +737,11 @@ defer read \ ---- 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 @@ -704,7 +776,7 @@ defer read cdr cdr car ; : assignment? ( obj -- obj bool ) - set-symbol tagged-list? ; + set!-symbol tagged-list? ; : assignment-var ( obj -- var ) cdr car ; @@ -720,7 +792,7 @@ defer read 2swap definition-var 2swap ( env var val ) - >R >R 2swap R> R> 2swap ( var val env ) + 2rot ( var val env ) define-var ok-symbol @@ -734,12 +806,71 @@ defer read 2swap assignment-var 2swap ( env var val ) - >R >R 2swap R> R> 2swap ( var val env ) + 2rot ( var val env ) set-var ok-symbol ; -: eval ( obj env -- result ) + +: 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 @@ -768,14 +899,46 @@ defer read 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 ---- {{{ +defer print + : printnum ( numobj -- ) drop 0 .R ; : printbool ( numobj -- ) @@ -825,7 +988,6 @@ defer read : printnil ( nilobj -- ) 2drop ." ()" ; -defer print : printpair ( pairobj -- ) 2dup car print @@ -835,14 +997,18 @@ 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 @@ -867,3 +1033,5 @@ defer print ; forth definitions + +\ vim:fdm=marker