The verb take is defined in later versions of J as {.
I recommend instead (this definition will not overwrite the one in z)
take =: (([ <. #@:]) {. ])
1 take i.2 NB. same as head
0
3 take i.2
0 1
(i.0) -: 1 take i.0
1
the reason this definition is better, is if you want the following, you can
still just use {.
3 {. i.2
0 1 0
1 {. i.0
0
{. i.0
0
my question is does anyone use the word take in code, such that it would break
under this redefinition? Even if you do, would you prefer having the word take
behave as above, and any code that depends on pure {. can just be replaced with
{. ?
one of the reasons the code is useful (regardless of name)
amdt =:2 : '(u (v{ ]))`(v"_)`]} ]'
2 + amdt (I.@:(2 < ])) i.5 NB. add 2 to items over 2
0 1 2 5 6
2 + amdt (I.@:(6 < ])) i.5 NB. no items pass filter, but no error, bc I.
returns i.0
0 1 2 3 4
2 + amdt (1 take I.@:(2 < ])) i.5 NB. just to first item over 2
0 1 2 5 4
2 + amdt (2 take I.@:(1 < ])) i.5 NB. just to first 2 items over 1
0 1 4 5 4
2 + amdt (1 take I.@:(8 < ])) i.5 NB. no error. no unwanted updates
0 1 2 3 4
2 + amdt (1 {. I.@:(8 < ])) i.5 NB. buggy - not intended
2 1 2 3 4
2 + amdt (2 {. I.@:(3 < ])) i.5 NB. buggy - not intended
2 1 2 3 6
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