Yes, that makes sense. The unquote is a neat way to fix that. One of these days, I will learn my lesson. Thanks Christopher!
On Fri, Mar 5, 2021 at 6:26 PM Christopher Baines <m...@cbaines.net> wrote: > > Tim Meehan <btmee...@gmail.com> writes: > > > I wanted to store a thunk in a hashtable so that I could look up its key > > and then run it later. Something like this: > > > > #! /usr/bin/guile > > !# > > > > (use-modules (ice-9 hash-table)) > > > > (define stuff (alist->hash-table > > '((a . (lambda () (display "event a\n"))) > > (b . (lambda () (display "event b\n"))) > > (c . (lambda () (display "event c\n")))))) > > > > (define res (hash-ref stuff 'a)) > > (res) > > > > But when I run it: > > Wrong type to apply: (lambda () (display "event a\n")) > > The lambda bit you've written is quoted. So you're asking Guile to apply > a list where the first element is the symbol 'lambda, the second is the > empty list, ... > > You probably want something like this, where you're creating a list of > pairs, where the car of the pair is a symbol, and the cdr is a procedure > (rather than a list). > > (define stuff (alist->hash-table > `((a . ,(lambda () (display "event a\n"))) > (b . ,(lambda () (display "event b\n"))) > (c . ,(lambda () (display "event c\n")))))) > > Does that make sense? >
