45 lines
1.2 KiB
Markdown
45 lines
1.2 KiB
Markdown
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### 5.1. Simple functions
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To create a recursive function we have to use this structure
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```Ocaml
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(*normal function*)
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# let f = expr -> 1) evaluate expr ; 2) create & link f to the result
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(*recursiv function*)
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# let rec f = expr -> 1) create f ; 2) evaluate expr ; 3) link f to the result
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```
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**Exmple with factorial function**
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```Ocaml
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# let rec fact = function
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| 0 -> 1
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| n -> n * fact(n-1)
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# fact 4;;
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-: int = 24
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```
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> ⚠️ CAML have a call stack limite (it will block with stack overflow if the limit is reach)
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**Basic expression**
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```Ocaml
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let rec f params =
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if stop condition then
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stop expression
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else
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recursive expression
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```
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To write a recurvise function we need two things
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1) There always is a stop case
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2) The parameters of a recursive call are different then its parent call, and go towards the stop condition
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### 5.2. Down
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```Ocaml
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# let rec countdown n =
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if n = 0 then
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print_int(0)
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else
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print_int(countdown (n-1));; |