> Does (g ∘ f)(x) mean g(f(x)) or f(g(x))? The function composition operator can... | Hacker News

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		herbstein on Oct 17, 2019 \| parent \| context \| favorite \| on: Haskell in Production > Does (g ∘ f)(x) mean g(f(x)) or f(g(x))? The function composition operator can be vocalized as, in this case, "g after f". That is, apply the f and then g. Translating '∘' into 'after' is the easiest way to understand it.

chrisdirkis on Oct 18, 2019 | [–]

Alternatively, I learnt it as "of" (from a mathematical standpoint). "(g ∘ f)(x) " is "g of f of x", so g(f(x))

phlakaton on Oct 18, 2019 | [–]

Haskell provides the (g . f) notation as the standard, and also has (f >>> g) notation buried in one of its more advanced libraries if anyone finds the right-to-left reading too disorienting.

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