diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 108 |
1 files changed, 94 insertions, 14 deletions
@@ -41187,13 +41187,15 @@ to discover the identities of the variables and functions which are used inside that form, whose definitions come from a specific, bounded scope surrounding that form. -.coNP Functions @ lexical-var-p and @ lexical-fun-p +.coNP Functions @, lexical-var-p @, lexical-fun-p @ lexical-symacro-p and @ lexical-macro-p .synb .mets (lexical-var-p < env << form ) .mets (lexical-fun-p < env << form ) +.mets (lexical-symacro-p < env << form ) +.mets (lexical-macro-p < env << form ) .syne .desc -These two functions are useful to macro writers. They are intended +These four functions are useful to macro writers. They are intended to be called from the bodies of macro expanders, such as the bodies of .code defmacro or @@ -41206,8 +41208,12 @@ via the special parameter. Using these functions, a macro can enquire whether a given .meta form -is a symbol which has a variable binding or a function binding -in the local lexical environment. +is, respectively, a symbol which has a variable binding, a function binding, +a symbol macro (defined by +.codn symacrolet ) +or a macro (defined by +.codn macrolet ) +in the environment of the macro's invocation. This information is known during macro expansion. The macro expander recognizes lexical function and variable bindings, because these bindings can shadow macros. @@ -41244,7 +41250,15 @@ Similarly, .code lexical-fun-p returns .code nil -for global functions. +for global functions, +.code lexical-symacro-p +returns +.code nil +for global symbol macros and +.code lexical-macro-p +returns +.code nil +for global macros. .TP* Example: @@ -41280,15 +41294,66 @@ for global functions. .TP* Note: -These functions do not call -.code macroexpand -on the form. In most cases, it is necessary for the macro writers -to do so. Not that in the above example, symbol -.code y -is classified as neither a lexical function nor variable. -However, it can be macro-expanded to -.code x -which is a lexical variable. +.coNP Function @ lexical-binding-kind +.synb +.mets (lexical-binding-kind < env << symbol ) +.syne +.desc +The +.code lexical-binding-kind +function inspects the macro-time environment +.meta env +to determine what kind of binding, if any, does +.meta symbol +have in the the variable namespace of that environment. + +If the innermost binding for +.meta symbol +is a variable binding, then either +.code :var +is returned if the variable is lexical, otherwise +.code nil +is returned if the variable is special. + +If the innermost binding for +.meta symbol +is a symbol macro, then +.code :symacro +is returned. + +In all other cases, +.code nil +is returned. The function does not consider global symbol macros +or global lexical variables. + +.coNP Function @ lexical-fun-binding-kind +.synb +.mets (lexical-fun-binding-kind < env << symbol ) +.syne +.desc +The +.code lexical-fun-binding-kind +function inspects the macro-time environment +.meta env +to determine what kind of binding, if any, does +.meta symbol +have in the the function namespace of that environment. + +If the innermost binding for +.meta symbol +is a function binding, then +.code :fun +is returned. + +If the innermost binding for +.meta symbol +is a macro, then +.code :macro +is returned. + +In all other cases, +.code nil +is returned. The function does not consider global macros or functions. .coNP Function @ lexical-lisp1-binding .synb @@ -41319,12 +41384,27 @@ If no such lexical binding is found, then the function returns .codn nil . +Note that +.code :var +is never returned for a special variable, but such a variable +can be shadowed by a symbol macro, in which case +.code :symacro +is returned. + Note that a .code nil return doesn't mean that the symbol doesn't have a lexical binding. It could have an operator macro lexical binding (a macro binding in the function namespace established by .codn macrolet ). +Unlike the +.code lexical-binding-kind +function, the +.code lexical-lisp1-binding +function never returns +.code :macro +because Lisp-1-style evaluation of symbols is blind to the existence of macros, +other than symbol macros. .coNP Operator @ defsymacro .synb |