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[Caml-list] Let-in vs beta-redex
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Date: -- (:)
From: John Gerard Malecki <johnm@a...>
Subject: RE: [Caml-list] Let-in vs beta-redex
Lukasz Stafiniak wrote (2003-09-01T18:15:54+0200):
 > Hi,
 > 
 > Is let-in more efficient than beta-redex or are they computationally
 > equivalent? Is let-in a syntax-sugar of beta-redex?

They may be conceptually different but they compile to pretty much teh
same thing.  A nice trick to learn about the code that ocamlc
generates is to use 'ocaml -dinstr'.  For example,


:; ocaml -dinstr
        Objective Caml version 3.07+beta 2

# let x = sin 2. in x *. x *. x;;
        const 2.
        ccall sin_float, 1
        push
        acc 0
        push
        acc 1
        push
        acc 2
        ccall mul_float, 2
        ccall mul_float, 2
        return 2

- : float = 0.751826944668992803
# (fun x -> x *. x *. x) (sin 2.);;
        const 2.
        ccall sin_float, 1
        push
        closure L1, 0
        appterm 1, 2
L1:     acc 0
        push
        acc 1
        push
        acc 2
        ccall mul_float, 2
        ccall mul_float, 2
        return 1

- : float = 0.751826944668992803
# 

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