Fuzion • Idioms • Idiom # 35: First-class function : compose

Idiom # 35: First-class function : compose

Code

Using manual function composition:

compose(f A -> B,
        g B -> C) A -> B => a -> g (f a)

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compose(f A -> B,
        g B -> C) A -> B => a -> g (f a)
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Using Function.compose:

compose(f A -> B,
        g B -> C) A -> B => a -> g (f a)

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compose(f A -> B,
        g B -> C) A -> B => a -> g (f a)
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Running Example

Using manual function composition:

ex35 is

  A(val i32) is
  B(val bool) is
  C(val String) is

  compose(f0 A -> B,
          g0 B -> C) A -> C => a -> g0 (f0 a)

  f A -> B := a -> B (a.val > 3)
  g B -> C := b -> C (if b.val then "T" else "F")

  fog := compose f g

  say (fog (A 10)).val
  say (fog (A 2)).val
  say (fog (A 0)).val

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ex35 is
  A(val i32) is
  B(val bool) is
  C(val String) is
  compose(f0 A -> B,
          g0 B -> C) A -> C => a -> g0 (f0 a)
  f A -> B := a -> B (a.val > 3)
  g B -> C := b -> C (if b.val then "T" else "F")
  fog := compose f g
  say (fog (A 10)).val
  say (fog (A 2)).val
  say (fog (A 0)).val
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Using Function.compose:

ex35a is

  A(val i32) is
  B(val bool) is
  C(val String) is

  f A -> B := a -> B (a.val > 3)
  g B -> C := b -> C (if b.val then "T" else "F")

  fog := g ∘ f

  say (fog (A 10)).val
  say (fog (A 2)).val
  say (fog (A 0)).val

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ex35a is
  A(val i32) is
  B(val bool) is
  C(val String) is
  f A -> B := a -> B (a.val > 3)
  g B -> C := b -> C (if b.val then "T" else "F")
  fog := g ∘ f
  say (fog (A 10)).val
  say (fog (A 2)).val
  say (fog (A 0)).val
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2024-07-01

next: Idiom # 36: First-class function : generic composition