hal sandhi is the general name for sandhi changes where the first sound is a consonant. Here are some simple examples:
क् + अ → ग
k + a → ga
ष् + त → ष्ट
ṣ + ta → ṣṭa
Many of the rules of hal sandhi appear after rule 8.2.1 (pūrvatrāsiddham), so they are asiddha with respect to prior rules. In plain English, this means that we must apply these rules in order.
hal sandhi is much more extensive than ac sandhi, and there is no simple picture of it we can provide. Instead, we will focus on four kinds of changes that we will see repeatedly throughout this series. These are:
changes involving the anusvāra
changes involving the visarga
changes of s to ṣ
changes of n to ṇ
This lesson will focus on the first two.
We have this new adhikāra:
Of a pada (word), …
The rules below also inherit the word saṃhitāyām (“in saṃhitā”) by anuvṛtti from an earlier rule.
Changes involving the anusvāra
Generally, the anusvāra is a sound that appears only due to sandhi. In the Aṣṭādhyāyī, the sound m and n become the anusvāra under different conditions.
First is a general rule about m at the end of a word. This rule inherits the term hali (“when a consonant follows”) from the rule before it:
मो ऽनुस्वारः। ८.३.२३
mo 'nusvāraḥ (8.3.23)
m becomes the anusvāra [at the end of a pada in saṃhitā when a consonant follows].
By this rule, we get results like this:
नगरम् गच्छामि → नगरं गच्छामि
nagaram gacchāmi → nagaraṃ gacchāmi
I go to the city.
We also have a second rule about m and n when they are not at the end of a pada:
नश्चापदान्तस्य झलि। ८.३.२४
naścāpadāntasya jhali (8.3.24)
naḥ ca a-pada-antasya jhali
[m] and n [become the anusvāra in saṃhitā] if not at the end of a pada, when followed by a jhal consonant.
By this rule, we get results like these:
मन्स्यसे → मंस्यसे
mansyase → maṃsyase
You will think.
रम्स्यसे → रंस्यसे
ramsyase → raṃsyase
You will delight.
But the anusvāra itself might be changed by later rules. These rules appear after the scope of 8.1.16 (padasya) has ended:
अनुस्वारस्य ययि परसवर्णः। ८.४.५८
anusvārasya yayi parasavarṇaḥ (8.4.58)
anusvārasya yayi para-savarṇaḥ
[In saṃhitā], the anusvāra becomes savarṇa to the following [sound] when followed by a yay sound,
वा पदान्तस्य। ८.४.५९
vā padāntasya (8.4.59)
[but] optionally at the end of a pada.
yay includes all consonants except for the sibilants (ś, ṣ, s, h). So the following changes are mandatory by rule 8.4.58:
अंकित → अङ्कित
aṃkita → aṅkita
रुंधन्ति → रुन्धन्ति
ruṃdhanti → rundhanti
And the following changes are optional, by rule 8.4.59:
नगरं गच्छामि → नगरं गच्छामि , नगरङ् गच्छामि
nagaraṃ gacchāmi → nagaraṃ gacchāmi , nagaraṅ gacchāmi
अहम् पृच्छामि → अहं पृच्छामि , अहम् पृच्छामि
aham pṛcchāmi → ahaṃ pṛcchāmi , aham pṛcchāmi
There are two ideas worth noting here. First, 8.4.59 is the first rule we've seen where we can choose whether to apply the rule or not. Many rules in the Aṣṭādhyāyī are optional, though certain choices do tend to become conventions over time.
Second, notice how the word rundhanti is treated by these rules. Since we must apply these rules in order, we have a derivation like this, where rundhanti is first changed by rule 8.3.23:
रुन्धन्ति → रुंधन्ति
rundhanti → ruṃdhanti
and then converted back to its original form by rule 8.4.58:
रुंधन्ति → रुन्धन्ति
ruṃdhanti → rundhanti
This kind of behavior is not uncommon in this section of the Aṣṭādhyāyī.
Rules that use the visarga
Like the anusvāra, the visarga is also a sound that appears only due to sandhi. In the Aṣṭādhyāyī, the sounds s and r become the visarga under different conditions.
Let's focus on how s changes, since those changes are more common. Our first rule is still in the scope of 8.1.16 (padasya) above:
ससजुषो रुः। ८.२.६६
sasajuṣo ruḥ (8.2.66)
The s [at the end of a pada] and the [last letter of the word] sajuṣ are replaced with ru̐.
sajuṣ is a rare word that we can set aside. ru̐, meanwhile, is a temporary symbol that we will replace in later rules. For example, it might be replaced by rule 8.1.15 below:
रो रि। ८.३.१४
ro ri (8.3.14)
The r [at the end of a pada] is replaced with lopa when r follows.
[The r at the end of a pada] is replaced with the visarjanīya (visarga) when khar or avasāna follows.
Let's discuss both of these rules in more detail. Rule 8.3.14 accounts for changes like the following:
द्वार् रोहिता → द्वा रोहिता
dvār rohitā → dvā rohitā
The door is red.
And the raḥ of rule 8.3.14 also includes ru̐.
What are khar and avasāna? khar is a pratyāhāra that refers to any unvoiced consonant. And avasāna is defined in rule 1.4.110:
Cessation [of speech] is called avasāna.
So r becomes the visarga when at the end of an utterance or when followed by an unvoiced consonant:
राम स् → राम रुँ → रामः
rāma s → rāma ru̐ → rāmaḥ
रामस् खादति → राम रुँ खादति → रामः खादति
rāmas khādati → rāma ru̐ khādati → rāmaḥ khādati
In addition to describing some common changes, the rules above also give a clearer idea of how rules in the asiddha section work. In the next lesson, we will finish our tour through sounds and sandhi by learning about two common changes that occur within a single word.