process
The contextual keyword process specifies the type of a user-defined function.
‘def process funname (params) with’, process definition
The modifier process indicates that the function processes vector arguments while maintaining in internal state.
table T = with
[| as N, as X |]
[| 0, 1 |]
[| 1, 2 |]
[| 2, -1 |]
def process sumOfSquares(x : number) with
keep sum = 0 // internal state, preserved while
sum = sum + x * x
return sum
T.CumulativeSum = sumOfSquares(T.X) scan T.N // 'scan' returns the whole vector
total = sumOfSquares(T.X) sort T.N // 'sort' only returns the last value
show table "" with T.N, T.X, T.CumulativeSum
// N,X,CumulativeSum
// 0,1,1
// 1,2,5
// 2,-1,6
show scalar "" with total // 6
The vector arguments are comma-separated:
def process sumOfSquares(x : number, y : number) with
keep sum = initSum // internal state, preserved while
sum = sum + x * x + y * y
return sum
The default value returned by the process when the vector arguments are empty (zero lines) is the default value of the datatype. However, this value can be overridden with the default keyword:
table T = with
[| as N, as X |]
[| 0, 1 |]
def process sumOfSquares(x : number) default 42 with // default value specified
keep sum = 0 // internal state, preserved while
sum = sum + x * x
return sum
// Filter 'T' to make it empty
where T.N != 0 // empty table 'T'
// Dummy sort (ordering does not matter, sum is commutative).
show scalar "" with sumOfSquares(T.X) sort 1 // 42
The initial state can be controlled by passing initialization arguments after a semi-colon (;) delimiter:
table T = with
[| as N, as X |]
[| 0, 1 |]
[| 1, 2 |]
[| 2, -1 |]
def process sumOfSquares(x : number; initSum : number) with
keep sum = initSum // internal state, preserved while
sum = sum + x * x
return sum
T.CumulativeSum = sumOfSquares(T.X; 3) scan T.N
show table "" with T.N, T.X, T.CumulativeSum
// N,X,CumulativeSum
// 0,1,4
// 1,2,8
// 2,-1,9
It is possible to use multiple vector arguments and multiple initialization arguments:
def process sumOfSquares(x : number, y : number; initX : number, initY : number) with
keep sum = initX + initY // internal state, preserved while
sum = sum + x * x + y * y
return sum