head

Operator#

head — copy leading values of input sequence

Synopsis#

head [ <const-expr> ]

Description#

The head operator copies the first N values from its input to its output and ends the sequence thereafter. N is given by <const-expr>, a compile-time constant expression that evaluates to a positive integer. If <const-expr> is not provided, the value of N defaults to 1.

Examples#

Grab first two values of arbitrary sequence

Query

head 2

Input

"foo"

[1,2,3]

Result

echo '1
"foo"
[1,2,3]' \
| super -z -c 'head 2' -

Grab first two values of arbitrary sequence, using a different representation of two

Query

head 1+1

Input

"foo"

[1,2,3]

Result

echo '1
"foo"
[1,2,3]' \
| super -z -c 'head 1+1' -

Grab the first record of a record sequence

Query

head

Input

{a:"hello"}

Result

echo '{a:"hello"}' \
| super -z -c 'head' -