Convert EO to φ-calculus Expression and Back
In the recently released version 0.34.0, we have implemented several changes to EO. Today, we will discuss the conversion of EO to φ-calculus expression and vice versa.
As you may know, φ-calculus is a formal model that we are attempting to use as a base for object-oriented programming languages, including EO.
From now on, it is possible to convert a program written in EO to a φ-calculus expression. Here’s how you can accomplish this in your personal project.
First you need to add eo-maven-plugin dependency:
<dependency>
<groupId>org.eolang</groupId>
<artifactId>eo-maven-plugin</artifactId>
<version>0.34.0</version> <!-- use 0.34.0 or younger -->
</dependency>
Conversion occurs in four stages: registration, parsing, optimization, and actual conversion. Therefore, include the corresponding goals in your build pipeline:
<build>
<plugins>
<plugin>
<groupId>org.eolang</groupId>
<artifactId>eo-maven-plugin</artifactId>
<version><!-- use the last version --></version>
<executions>
<execution>
<id>convert</id>
<goals>
<goal>register</goal>
<goal>parse</goal>
<goal>optimize</goal>
<goal>xmir-to-phi</goal>
</goals>
</execution>
<configuration>
<sourcesDir><!-- Where .eo source is placed, src/main/eo by default --></sourcesDir>
<phiOutputDir><!-- Where .phi files are placed target/eo/phi by default --></phiOutputDir>
</configuration>
</executions>
</plugin>
</plugins>
</build>
Now, you are ready to convert an EO program to a φ-calculus expression. Place the .eo file in the source
directory and run your Maven project. When it’s done, files with the .phi extension are placed in
the phiOutputDir directory.
You may also convert a φ-calculus expression back to EO. For this, your build pipeline should look like:
<build>
<plugins>
<plugin>
<groupId>org.eolang</groupId>
<artifactId>eo-maven-plugin</artifactId>
<version><!-- use the last version --></version>
<executions>
<execution>
<id>convert</id>
<goals>
<goal>phi-to-xmir</goal>
<goal>optimize</goal>
<goal>print</goal>
</goals>
</execution>
<configuration>
<unphiInputDir><!-- Where .phi source is placed, target/eo/phi by default --></unphiInputDir>
<printSourcesDir>${project.basedir}/target/eo/2-optimize</printSourcesDir> <!-- /src/main/xmir by default -->
<printOutputDir><!-- Where result .eo files are placed, target/generated-sources/eo by default --></printOutputDir>
</configuration>
</executions>
</plugin>
</plugins>
</build>
When it’s done result .eo files are placed in output printOutputDir directory.
Here’s an example of how the EO Fibonacci program looks in φ-calculus (you can find more examples here):
+package eo.example
[n] > fibonacci
if. > @
lt.
n
2
n
plus.
fibonacci
n.minus 1
fibonacci
n.minus 2
Its XMIR representation (default location is
target/eo/2-optimize):
<?xml version="1.0" encoding="UTF-8"?>
<program dob="2023-03-19T00:00:00"
ms="12"
name="foo.x.main"
revision="1234567"
source="/var/folders/xj/f4s949893tq37zzw0pdmd68h0000gn/T/junit2727451398454004374/foo/x/main.eo"
time="2023-12-13T10:04:53.022835Z"
version="0.0-SNAPSHOT">
<!--This is XMIR - a dialect of XML, which is used to present a parsed EO program. For more information please visit https://news.eolang.org/2022-11-25-xmir-guide.html-->
<listing>+package eo.example
[n] > fibonacci
if. > @
lt.
n
2
n
plus.
fibonacci
n.minus 1
fibonacci
n.minus 2
</listing>
<errors>
<error check="missing-home"
line=""
severity="warning"
sheet="mandatory-home-meta"
step="0">Missing home</error>
<error check="missing-version-meta"
line=""
severity="warning"
sheet="mandatory-version-meta"
step="0">Missing version meta</error>
</errors>
<sheets>
<sheet>not-empty-atoms</sheet>
<sheet>duplicate-names</sheet>
<sheet>many-free-attributes</sheet>
<sheet>broken-aliases</sheet>
<sheet>duplicate-aliases</sheet>
<sheet>global-nonames</sheet>
<sheet>same-line-names</sheet>
<sheet>self-naming</sheet>
<sheet>cti-adds-errors</sheet>
<sheet>add-refs</sheet>
<sheet>wrap-method-calls</sheet>
<sheet>expand-qqs</sheet>
<sheet>add-probes</sheet>
<sheet>vars-float-up</sheet>
<sheet>add-refs</sheet>
<sheet>sparse-decoration</sheet>
<sheet>unsorted-metas</sheet>
<sheet>incorrect-architect</sheet>
<sheet>incorrect-home</sheet>
<sheet>incorrect-version</sheet>
<sheet>expand-aliases</sheet>
<sheet>resolve-aliases</sheet>
<sheet>add-refs</sheet>
<sheet>add-default-package</sheet>
<sheet>broken-refs</sheet>
<sheet>unknown-names</sheet>
<sheet>noname-attributes</sheet>
<sheet>duplicate-names</sheet>
<sheet>duplicate-metas</sheet>
<sheet>mandatory-package-meta</sheet>
<sheet>mandatory-home-meta</sheet>
<sheet>mandatory-version-meta</sheet>
<sheet>correct-package-meta</sheet>
<sheet>prohibited-package</sheet>
<sheet>external-weak-typed-atoms</sheet>
<sheet>unused-aliases</sheet>
<sheet>unit-test-without-phi</sheet>
<sheet>explicit-data</sheet>
<sheet>set-locators</sheet>
</sheets>
<license/>
<metas>
<meta line="1">
<head>package</head>
<tail>eo.example</tail>
<part>eo.example</part>
</meta>
<meta line="4">
<head>probe</head>
<tail>n.lt.if</tail>
<part>n.lt.if</part>
</meta>
</metas>
<objects>
<o abstract=""
line="3"
loc="Φ.eo.example.fibonacci"
name="fibonacci"
pos="0">
<o line="3" loc="Φ.eo.example.fibonacci.n" name="n" pos="1"/>
<o base=".if"
line="4"
loc="Φ.eo.example.fibonacci.φ"
name="@"
pos="2">
<o base=".lt" line="5" loc="Φ.eo.example.fibonacci.φ.ρ" pos="4">
<o base="n"
line="6"
loc="Φ.eo.example.fibonacci.φ.ρ.ρ"
pos="6"
ref="3"/>
<o base="org.eolang.int"
line="7"
loc="Φ.eo.example.fibonacci.φ.ρ.α0"
pos="6">
<o base="org.eolang.bytes"
data="bytes"
loc="Φ.eo.example.fibonacci.φ.ρ.α0.α0">00 00 00 00 00 00 00 02</o>
</o>
</o>
<o base="n"
line="8"
loc="Φ.eo.example.fibonacci.φ.α0"
pos="4"
ref="3"/>
<o base=".plus" line="9" loc="Φ.eo.example.fibonacci.φ.α1" pos="4">
<o base="fibonacci"
line="10"
loc="Φ.eo.example.fibonacci.φ.α1.ρ"
pos="6"
ref="3">
<o base=".minus"
line="11"
loc="Φ.eo.example.fibonacci.φ.α1.ρ.α0"
pos="9">
<o base="n"
line="11"
loc="Φ.eo.example.fibonacci.φ.α1.ρ.α0.ρ"
pos="8"
ref="3"/>
<o base="org.eolang.int"
line="11"
loc="Φ.eo.example.fibonacci.φ.α1.ρ.α0.α0"
pos="16">
<o base="org.eolang.bytes"
data="bytes"
loc="Φ.eo.example.fibonacci.φ.α1.ρ.α0.α0.α0">00 00 00 00 00 00 00 01</o>
</o>
</o>
</o>
<o base="fibonacci"
line="12"
loc="Φ.eo.example.fibonacci.φ.α1.α0"
pos="6"
ref="3">
<o base=".minus"
line="13"
loc="Φ.eo.example.fibonacci.φ.α1.α0.α0"
pos="9">
<o base="n"
line="13"
loc="Φ.eo.example.fibonacci.φ.α1.α0.α0.ρ"
pos="8"
ref="3"/>
<o base="org.eolang.int"
line="13"
loc="Φ.eo.example.fibonacci.φ.α1.α0.α0.α0"
pos="16">
<o base="org.eolang.bytes"
data="bytes"
loc="Φ.eo.example.fibonacci.φ.α1.α0.α0.α0.α0">00 00 00 00 00 00 00 02</o>
</o>
</o>
</o>
</o>
</o>
</o>
</objects>
</program>
And its φ-calculus representation:
{
eo ↦ ⟦
example ↦ ⟦
fibonacci ↦ ⟦
n ↦ ∅,
φ ↦ ξ.n.lt(
α0 ↦ Φ.org.eolang.int(
α0 ↦ Φ.org.eolang.bytes(Δ ⤍ 00-00-00-00-00-00-00-02)
)
).if(
α0 ↦ ξ.n,
α1 ↦ ξ.ρ.fibonacci(
α0 ↦ ξ.n.minus(
α0 ↦ Φ.org.eolang.int(
α0 ↦ Φ.org.eolang.bytes(Δ ⤍ 00-00-00-00-00-00-00-01)
)
)
).plus(
α0 ↦ ξ.ρ.fibonacci(
α0 ↦ ξ.n.minus(
α0 ↦ Φ.org.eolang.int(
α0 ↦ Φ.org.eolang.bytes(Δ ⤍ 00-00-00-00-00-00-00-02)
)
)
)
)
)
⟧,
λ ⤍ Package
⟧,
λ ⤍ Package
⟧
}
That’s it for now, be in touch.