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Comment by solomonb | Hacker News Reader

    mySubroutine = do
      foo <- mkFoo
      bar <- mkbar foo
      mkBaz bar
    
    mySubroutineV2 =
      mkFoo >>= \foo ->
        mkBar foo >>= \bar ->
          mkBaz bar

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Note that this is same desugaring for normal let

  let x = y in F   <===>   (\x.F)(y)

just replacing function application with a different function (>>=).

You can desugar let bindings that way but often times (as I believe is the case in GHC) you have a `Let` term in your AST.

This is not the case in Haskell, because let-bindings can be self-referential, while lambdas cannot (without using a fixed point combinator). Also, in most functional languages, a let-binding causes type generalisation, which is not the case for a lambda.

Not exactly the same: `x` is given a polymorphic type (in F) in Haskell (restricted to values in ML) whereas the unannotated let-over-lambda will give `x`a monomorphic type.

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