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pipe



pipe() is a utility for chaining transformations together. It actually has nothing to do with callbags specifically, its just particularly useful with callbag utilities.

1linkfunction pipe<A, B, C>(

2link  a: A,

3link  b: (a: A) => B,

4link  c: (b: B) => C

5link): C


This code:

1linkimport { pipe, interval, map, filter, subscribe } from 'callbag-common';

2link

3linkpipe(

4link  interval(1000),

5link  map(x => x * 3),

6link  filter(x => x % 2 === 0),

7link  subscribe(console.log)

8link)


Is equivalent to this code:

1linkimport { interval, map, filter, subscribe } from 'callbag-common';

2link

3linklet source = interval(1000);

4linksource = map(x => x * 3)(source);

5linksource = filter(x => x % 2 === 0)(source);

6linksubscribe(console.log)(source);


In other words:

1linkpipe(a, b, c, d) === d(c(b(a)))



👉 You can also use pipe() to easily build new utilities and operators:

1link​const multiply = k => src => pipe(src, map(n => n * k));

2link​

3link​pipe(

4link​  interval(1000),

5link​  multiply(10),

6link​  subscribe(console.log)

7link​)

8link​

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