Lambda calculus parser & compiler.

2+2.lambda

(λ+2.+22)(λmnfx.mf(nfx))((λs0.s(s0))(λnfx.f(nfx))(λfx.x))

boolean.lambda

(λtf!&|.!(&f(|tf)))(λtf.t)(λtf.f)(λp.λtf.pft)(λpq.pqp)(λpq.ppq)

lambda.pegjs

{
// Compilation
function compilejs(exp) {
 if(exp.length == 1) {
  return exp[0].replace(/[^a-zA-Z_$]/g, function(c) {
   return "_$" + c.charCodeAt(0).toString(16) + "$_ /* " + c + " */"
  })
 } else if(exp.length == 2) {
  return compilejs(exp[0]) + "(" + compilejs(exp[1]) + ")"
 } else if(exp.length == 3) {
  return "(" + "function(" + compilejs(exp[1]) + ") {\n  "
  + "return " + compilejs(exp[2]).trim().split('\n').map(function(l) {
   return ' ' + l
  }).join('\n')
  + "\n})"
 }
}
// Output
function print(code) {
 return code + '\n====>\nRaw:\n' + (function() {
  try {
   var f = eval(code)
   console.log(f)
   var n = dechurch(f)
   var b = churchbool(f)
   return f
    + '\nChurch number: ' + n
    + "\nChurch boolean: " + b
  } catch(e) {
   return 'Error: ' + e
  }
 })()
}
function dechurch(v) {
 try {
  var n = v(function(x) { return x + 1 })(0)
  if(typeof n == "number") {
   return n
  } else {
   return null
  }
 } catch(e) { return null }
}
function churchbool (v) {
 try {
  var b = v(true)(false)
  if(typeof b == "boolean") {
   return b
  } else {
   return null
  }
 } catch(e) { return null }
}
//Sugar
function lambda(a, r) {
 if(a.length == 1) {a
  return ['lambda', a[0], r]
 } else {
  return ['lambda', a[0], lambda(a.slice(1), r)]
 }
}
function call(f, a) {
 if(a.length == 1) {
  return [f, a[0]]
 } else {
  return [call(f, a.slice(0, -1)), a[a.length-1]]
 }
}
}

prog
 = e:(barecall / exp) { return print(compilejs(e)) }

exp
 = var
 / call
 / func
 / lparen e:exp rparen { return e }

var
 = n:(!lambda $[^\(\)\\\\. ])
 { return [n[1]] }

call
 = lparen f:exp a:(space? exp)+ rparen
 {
  return call(f, a.map(function(e) {
   return e[1]
  }))
 }

barecall
 = f:exp a:(space? exp)+
 {
  return call(f, a.map(function(e) {
   return e[1]
  }))
 }

func
 = lambda a:var+ dot r:(barecall / exp) { return lambda(a, r) }


lparen = "("
rparen = ")"
dot    = '.'
space  = ' '
lambda = ("λ" / "\\") { return "λ" }

_ = [\r\n\t ]*