Hi, Joel,
>
> > Nor does the technique generalize:
> >
> > mapper: func ['f] [func [block] compose [foreach element
> > block [(f)
> > element]]]
>
> Sure it does, with one little difference:
>
> mapper: func ['f][func [block] compose/deep [
> foreach element block [(f) element]]
> ]
>
> l: mapper (func [x][prin odd? x])
> l [1 2 3 4 5]
> truefalsetruefalsetrue
>
My experience with other languages leads me to want a 'map that can
take an argument function, returning a function which can be applied
to a block to yield a block of (corresponding) results, as in
(HYPOTHETICAL):
>> map: ; MISSING (I have no idea at this point)
>> map-odd: map odd?
>> map-odd [1 2 3 4 5]
== [true false true false true]
Could someone (Jeff?) supply the definition for 'map missing above?
-jn-
Here you are:
map: func [
f [any-function!]
] [
func [
blk [block!]
/local result
] [
result: copy []
foreach x blk [
append/only result do compose [(:f) x]
]
]
]
;Example:
>> mapodd: map :odd?
>> mapodd [1 2 3 4 5]
== [true false true false true]
Ladislav
