moore%defmacro.utah.edu@cs.utah.edu (Tim Moore) (06/14/91)
In article <ALANR.91Jun14122852@chopin.media-lab.media.mit.edu> alanr@chopin.media-lab.media.mit.edu (Alan Ruttenberg) writes: > >I have a question about the interaction of flet and macrolet. > >(defun foo () ''outside) >(flet ((foo () ''inside)) (macrolet ((bar () (foo))) (bar))) > >Should this return a) 'outside b) 'inside c) signal an error > >I've convinced myself that it shouldn't return 'inside. Reasoning: >Flet binds, at run time, the local function foo. Macrolet is expanded >at compile time, so the function is not yet available. If one writes instead >(flet ((foo () ''inside)) (macrolet ((bar () '(foo))) (bar))), then it makes >sense to return 'inside. It depends. In Lisps based on the original CLtL, local macro functions are defined in the global environment. The local binding of foo isn't visible, so the form returns OUTSIDE. However, X3J13 changed the definition of macrolet so that macro functions are defined "in the lexical environment in which the MACROLET form appears.." (pg 153, CLtL2). Refering to a local variable or function binding is "undefined". The above form might return INSIDE in some interpreters, OUTSIDE in others, or it might signal an error. Compiling this form will probably signal an error. -- Tim Moore moore@cs.utah.edu {bellcore,hplabs}!utah-cs!moore "Ah, youth. Ah, statute of limitations." -John Waters
alanr@chopin.media-lab.media.mit.edu (Alan Ruttenberg) (06/15/91)
I have a question about the interaction of flet and macrolet. (defun foo () ''outside) (flet ((foo () ''inside)) (macrolet ((bar () (foo))) (bar))) Should this return a) 'outside b) 'inside c) signal an error I've convinced myself that it shouldn't return 'inside. Reasoning: Flet binds, at run time, the local function foo. Macrolet is expanded at compile time, so the function is not yet available. If one writes instead (flet ((foo () ''inside)) (macrolet ((bar () '(foo))) (bar))), then it makes sense to return 'inside. But I'm not sure about whether it should return 'outside. I vote yes, and a friend votes no. -alan