How can I align this equation well?

Question

I try formulate some lambda expression in lambda calculus. It is similar to a code, but I have to use align environment because it contains math symbols. I wonder how I can formulate its structures better? The current one has a lot of unneeded spaces in between, although it captures some of what I want it to look like.

\begin{align*}
\text{cell} = & \text{rec} (& \lambda b.&\lambda c.  &\lambda m.&  \\
              &             & \text{if} &(\text{get?}&(m),      &  \\
              &             &           & \text{seq} &(\text{send}&(\text{contents}(m), c), & \text{ready}(b(c))), \\
              &             &           & \text{if}  &(\text{set?}&(m), & \\
              &             &           &            & \text{ready}&(b(\text{contents}(m))), & \\
              &             &           &            & \text{ready}&(b(c))))) 
\end{align*}

Here is what I want

Answer 1

Not quite what you want, but how about this:

\documentclass{article}
\usepackage{mathtools, amssymb}

\begin{document}

\begin{alignat*}{4}
\text{cell} ={} & \text{rec} ( & & \lambda\mathrlap{ b.\lambda c. \lambda m.} \\
               & & & \text{if} &( & \mathrlap{\text{get?}(m),} \\
               & & & & & \text{seq} &( & \text{send}(\text{contents}(m), c), \\
               & & & & & & & \text{ready}(b(c))), \\
               & & & & & \text{if}\:( & & \text{set?}(m),\\
               & & & & & & & \text{ready}(b(\text{contents}(m))), \\
               & & & & & & & \text{ready}(b(c)))))
\end{alignat*}

\end{document} 

Answer 2

It is a bit hard coding but easiest and enough fast (is it what You need?):

\documentclass{article}
\usepackage{amsfonts}
\usepackage{amsmath}
\usepackage{amssymb}




\begin{document}
\begin{align*}
\text{cell} =  \text{rec} (&\lambda b.\lambda c.\lambda m.\\
                           &\text{if} (\text{get?}(m), \\
                           &          \quad \text{seq} (\text{send}(\text{contents}(m), c),\\ 
                           & \qquad \quad \text{ready}(b(c))), \\
                           & \quad\text{if}  (\text{set?}(m), \\
                           &\qquad\text{ready}(b(\text{contents}(m))), \\
                           &\qquad\text{ready}(b(c))))) 
\end{align*}
\end{document}

Answer 3

Probabily your code can be more fine if it is used lambdax package here on this link, https://ctan.org/pkg/lambdax

To work with this package you should download the lambdax.sty and keyparse.sty from your TeX distribuition (on MikTeX the answer is yes.)

Reading the explanation there is written This package provides Lambda expressions. that it is your objective.

Here there is a small example taken from https://github.com/rogard/lambdax/blob/main/testfiles/lambdax-001.lvt

\documentclass{article}
\usepackage{lambdax}
\begin{document}
\ExplSyntaxOn
\START
\box_new:N \l_tmp_box
\hbox_set:Nn \l_tmp_box{\LambdaX{(#1)}{x}}
\box_use:N \l_tmp_box
%\END
\ExplSyntaxOff
\end{document}