On Mon, Jun 25, 2018 at 9:02 PM, Aaron Hill <lilyp...@hillvisions.com> wrote:
> On 2018-06-25 17:25, Freeman Gilmore wrote: > >> On Mon, Jun 25, 2018 at 9:29 AM, Urs Liska <li...@openlilylib.org> wrote: >>> >>>> Try this file: >>>> >>>> \version "2.19.80" >>>> >>>> #(let >>>> ((something 'something-else)) >>>> (display something) >>>> (newline) >>>> (display something)(display something)) >>>> >>> >> In you first example #(let...) what function does 'let' preform? >> > > Here is the reference on `let` for Guile: > > https://www.gnu.org/software/guile/manual/html_node/Local-Bi > ndings.html#Local-Bindings > > Without repeating verbatim what is there, `let` is a way of defining > locally-scoped variables. > > In the example above, `something` is being defined as `'something-else`, > and it is being referenced later in the function body several times. But > as a local variable, `something` is ephemeral and will no longer be valid > outside of the scope of the let-block body. Consider: > > %%%% > #(let > ((a 1) (b 2)) > (display (+ a b)) #! should output 3 !# > (let > ((a b) (c 3)) > (display (+ a c)) #! should output 5 !# > ) > (display a) #! should output 1 !# > #!(display c)!# #! error: unbound variable c !# > ) > %%%% > > The inner let here redefines `a` while also defining `c`. Outside of its > body, the original value of `a` is effectively restored but then `c` is no > longer bound so you cannot refer to it. > > Hope that helps, > > -- Aaron Hill > Thanks Aaron: The example was very clear. Now I am reading the reference next. Thank you, ƒg > > _______________________________________________ > lilypond-user mailing list > lilypond-user@gnu.org > https://lists.gnu.org/mailman/listinfo/lilypond-user >
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